Mechanistic associations between obesity and colorectal cancer remain unclear. In this study, we investigated whether adipokines are risk factors for colorectal cancer and whether they may mediate its association with obesity. In a case–cohort study nested within the Women’s Health Initiative cohort of postmenopausal women, baseline plasma samples from 457 colorectal cancer cases and 841 subcohort subjects were assayed for seven adipokines—adiponectin, leptin, plasminogen activator inhibitor-1 (PAI-1), resistin, hepatocyte growth factor, interleukin-6 (IL-6), and TNF-α. Serum insulin and estradiol values measured previously were also available for data analysis. After adjusting for age, race, smoking, colonoscopy history, and estrogen level, a low level of antiinflammatory adiponectin and high levels of proinflammatory leptin, PAI-1, and IL-6 were associated with increased colorectal cancer risk, though only leptin remained significant after further adjustment for insulin [HRs comparing extreme quartiles (HRQ4–Q1), 1.84; 95% CI, 1.17–2.90]. Mediation analyses showed that leptin and insulin partially explained the association between waist circumference and colorectal cancer and attenuated it by 25% and 37%, respectively, with insulin being a significant mediator (P = 0.041). Our findings support the conclusion that adipokines involved in inflammation are associated with colorectal cancer risk, but that their effects may be mediated mostly by insulin, with leptin exerting an independent effect. Hyperinsulinemia and hyperleptinemia may therefore partially explain the adiposity association with colorectal cancer in postmenopausal women.
Human papillomavirus (HPV) is detected in nearly all cervical cancers and approximately half of vaginal cancers. However, vaginal cancer is an order of magnitude less common than cervical cancer, not only in the general population but also among women with HIV/AIDS. It is interesting therefore that recent studies found that HPV was common in both normal vaginal and cervical tissue, with higher prevalence of non-oncogenic HPV types in the vagina. In the current investigation, we prospectively examined HPV infection in 86 HIV-positive and 17 HIV-negative women who underwent hysterectomy during follow-up in a longitudinal cohort. Cervicovaginal lavage specimens were obtained semi-annually and tested for HPV DNA by PCR. To address possible selection biases associated with having a hysterectomy, subjects acted as their own comparison group – before versus after hysterectomy. The average HPV prevalence was higher in HIV-positive than HIV-negative women both before (59% versus 12%; P<0.001) and after hysterectomy (56% versus 6%; P<0.001). Multivariate random effects models (within-individual comparisons) demonstrated significantly lower HPV prevalence (odds ratio [OR]=0.71; 95% confidence interval [CI]=0.59-0.85) after hysterectomy. The association of HPV prevalence with hysterectomy was similar among HIV-positive and HIV-negative women. However, hysterectomy had greater effects on oncogenic (OR=0.48; 95%CI=0.35-0.66) than non-oncogenic HPV types (OR=0.89; 95%CI=0.71-1.11; Pinteraction=0.002). Overall, we observed greater reductions in oncogenic than non-oncogenic HPV prevalence following hysterectomy. If correct, these data could suggest that oncogenic HPV have greater tropism for cervical compared with vaginal epithelium, consistent with the lower incidence of vaginal than cervical cancer.
vaginal; HPV; hysterectomy; viral tropism; HIV
Coffee drinking may be associated with reduced risk of endometrial cancer; however, prospective data are limited. Further, it is not clear whether any association between coffee and endometrial cancer differs according to coffee caffeine content. The association of coffee drinking with incidence of endometrial cancer was evaluated among 226,732 women, aged 50–71, enrolled in the NIH-AARP Diet and Health Study who completed a baseline epidemiologic questionnaire. Following a mean 9.3 years of follow-up, data were available for 1,486 incident endometrial cancer cases. Cox proportional hazards models were used to estimate associations of coffee with endometrial cancer incidence. Sub-group analyses were performed according to smoking status, hormone therapy use (HT) and body habitus. Coffee drinking was inversely related to incidence of endometrial cancer (Hazard Ratio [HR] comparing drinking of >3 cups/day versus no cups=0.64, 95%CI, 0.51–0.80; Ptrend= 0.0004). The association of coffee with endometrial cancer risk was apparent for consumption of both regular (HR per cup= 0.90, 95%CI, 0.86–0.95) and decaffeinated coffee (HR per cup=0.93, 95%CI, 0.87–0.99). The relation of coffee with endometrial cancer incidence varied significantly by HT use (Pinteraction=0.03) with an association only apparent among HT-never users (HR comparing drinking >3 cups/day versus no cups= 0.54, 95%CI, 0.41–0.72; Ptrend=0.0005). Endometrial cancer incidence appears to be reduced among women that habitually drink coffee, an association that does not differ according to caffeine content.
Inflammation and hemostasis perturbation may be involved in vascular complications of HIV infection. We examined atherogenic biomarkers and subclinical atherosclerosis in HIV-infected adults before and after beginning highly-active antiretroviral therapy (HAART).
In the Women's Interagency HIV Study (WIHS), 127 HIV-infected women studied pre- and post-HAART were matched to HIV-uninfected controls. Six semi-annual measurements of soluble CD14, tumor necrosis factor (TNF)-alpha, soluble interleukin (IL)-2 receptor, IL-6, IL-10, monocyte chemoattractant protein (MCP)-1, D-dimer, and fibrinogen were obtained. Carotid artery intima-media thickness (CIMT) was measured by B-mode ultrasound.
Relative to HIV-uninfected controls, HAART-naïve HIV-infected women had elevated levels of soluble CD14 (1945 vs 1662 ng/mL, Wilcoxon signed rank P<0.0001), TNF-alpha (6.3 vs 3.4 pg/mL, P<0.0001), soluble IL-2 receptor (1587 vs 949 pg/mL, P<0.0001), IL-10 (3.3 vs 1.9 pg/mL, P<0.0001), MCP-1 (190 vs 163 pg/mL, P<0.0001) and D-dimer (0.43 vs 0.31 µg/mL, P<0.01). Elevated biomarker levels declined after HAART. While most biomarkers normalized to HIV-uninfected levels, in women on effective HAART, TNF-alpha levels remained elevated compared to HIV-uninfected women (+0.8 pg/mL, P=0.0002). Higher post-HAART levels of soluble IL-2 receptor (P=0.02), IL-6 (P=0.05), and D-dimer (P=0.03) were associated with increased CIMT.
Untreated HIV infection is associated with abnormal hemostasis (e.g., D-dimer), and pro-atherogenic (e.g., TNF-alpha) and anti-atherogenic (e.g., IL-10) inflammatory markers. HAART reduces most inflammatory mediators to HIV-uninfected levels. Increased inflammation and hemostasis are associated with subclinical atherosclerosis in recently treated women. These findings have potential implications for long-term risk of cardiovascular disease in HIV-infected patients, even with effective therapy.
antiretroviral therapy; cardiovascular diseases; cytokines; hemostasis; HIV; inflammation
Polytomous logistic regression models are commonly used in case-control studies of cancer to directly compare the risks associated with an exposure variable across multiple cancer subtypes. However, the validity, accuracy and efficiency of this approach for prospective cohort studies have not been formally evaluated.
We investigated the performance of the polytomous logistic regression model and compared it to an alternative approach based on a joint Cox proportional hazards model using simulation studies. We then applied both methods to a prospective cohort study to assess whether the association of breast cancer with body size differs according to estrogen and progesterone receptor-defined subtypes.
Our simulations showed that the polytomous logistic regression model but not the joint Cox regression model yielded biased results in comparing exposure and disease subtype associations when the baseline hazards for different disease subtypes are non-proportional. For this reason, an analysis of a real data set was based on the joint Cox proportional hazards model and showed that body size has a significantly greater association with estrogen and progesterone positive breast cancer than with other subtypes.
Because of the limitations of the polytomous logistic regression model for the comparison of exposure-disease associations across disease subtypes, the joint Cox proportional hazards model is recommended over the polytomous logistic regression model in prospective cohort studies.
The paper will promote the use of the joint Cox model in a prospective cohort study. Examples of SAS and S-plus programming codes are provided to facilitate use by non-statisticians.
time to event data; proportional hazards functions; robust variance; competing risk
Case-cohort studies have become common in epidemiological studies of rare disease, with Cox regression models the principal method used in their analysis. However, no appropriate procedures to assess the assumption of proportional hazards of case-cohort Cox models have been proposed.
We extended the correlation test based on Schoenfeld residuals, an approach used to evaluate the proportionality of hazards in standard Cox models. Specifically, pseudolikelihood functions were used to define “case-cohort Schoenfeld residuals”, and then the correlation of these residuals with each of three functions of event time (i.e., the event time itself, rank order, Kaplan-Meier estimates) was determined. The performances of the proposed tests were examined using simulation studies. We then applied these methods to data from a previously published case-cohort investigation of the insulin/IGF-axis and colorectal cancer.
Simulation studies showed that each of the three correlation tests accurately detected non-proportionality. Application of the proposed tests to the example case-cohort investigation dataset showed that the Cox proportional hazards assumption was not satisfied for certain exposure variables in that study, an issue we addressed through use of available, alternative analytical approaches.
The proposed correlation tests provide a simple and accurate approach for testing the proportional hazards assumption of Cox models in case-cohort analysis. Evaluation of the proportional hazards assumption is essential since its violation raises questions regarding the validity of Cox model results which, if unrecognized, could result in the publication of erroneous scientific findings.
Proportional hazards; Schoenfeld residuals; Case-cohort studies; Cox models
Background. Cytomegalovirus (CMV) infection has been implicated in immune activation and accelerated progression of immunodeficiency from human immunodeficiency virus (HIV) coinfection. We hypothesized that CMV is associated with vascular disease in HIV-infected adults.
Methods. In the Women's Interagency HIV Study, we studied 601 HIV-infected and 90 HIV-uninfected participants. We assessed the association of CMV immunoglobulin G (IgG) level with carotid artery intima-media thickness, carotid artery distensibility, Young's elastic modulus, and blood pressures. Multivariable models adjusted for age, race/ethnicity, smoking, diabetes, and body mass index.
Results. Mean CMV IgG levels were higher in HIV-infected women compared with HIV-uninfected women (P < .01). Among HIV-infected women, higher CMV IgG level was associated with decreased carotid artery distensibility (P < .01) and increased Young's modulus (P = .02). Higher CMV IgG antibody level was associated with increased prevalence of carotid artery lesions among HIV-infected women who achieved HIV suppression on antiretroviral therapy, but not among viremic or untreated HIV-infected women. Adjustment for Epstein–Barr virus antibody levels and C-reactive protein levels had no effect on the associations between CMV IgG levels and vascular parameters.
Conclusions. Cytomegalovirus antibody titers are increased in HIV-infected women and associated with subclinical cardiovascular disease. Host responses to CMV may be abnormal in HIV infection and associated with clinical disease.
U.S. cervical cancer screening guidelines for HIV-uninfected women 30 years of age and older have recently been revised, increasing the suggested interval between Pap tests from three years to five years among those with normal cervical cytology (the Pap test) who test negative for oncogenic human papillomavirus (HPV). Whether a three-year or five-year screening interval might be used in HIV-infected women who are cytologically normal and oncogenic HPV-negative is unknown.
To determine the risk of cervical pre-cancer or cancer defined cytologically (high-grade squamous intraepithelial lesions or greater [HSIL+]) or histologically (cervical intraepithelial neoplasia 2 or greater [CIN-2+]), as two separate endpoints, in HIV-infected women and HIV-uninfected women who at baseline had a normal Pap test and were negative for oncogenic HPV.
Design, Setting and Participants
Participants included 420 HIV-infected women and 279 HIV-uninfected women with normal cervical cytology at their enrollment in a multi-institutional cohort, between October 1, 2001 and September 30, 2002, with follow-up through April 30, 2011. Clinical sites were in the Bronx, Brooklyn, Chicago, Los Angeles, San Francisco, and Washington, DC. Semi-annual visits included Pap testing and, if indicated, cervical biopsy. Cervicovaginal lavage specimens from enrollment were tested for HPV DNA using PCR. The primary analysis was truncated at five years of follow-up.
Main Outcome Measure
The five-year cumulative incidence of cervical pre-cancer and cancer.
No oncogenic HPV was detected in 369 (88%; 95% CI, 84%-91%) of the HIV-infected women and 255 (91%; 95% CI, 88%-94%) of the HIV-uninfected women with normal cervical cytology at enrollment. Among these oncogenic HPV-negative women two cases of HSIL+ were observed; an HIV-uninfected woman and an HIV-infected woman with a CD4 cell count of 500/μL or greater. Histologic data were obtained from four of the six sites. There were six cases of CIN-2+ in N=145 HIV-uninfected women (cumulative incidence = 5% [95% CI, 1%-8%]) and nine cases in N=219 HIV-infected women (cumulative incidence = 5% [95% CI, 2%-8%]). This included one case of CIN-2+ in N=44 oncogenic HPV-negative HIV-infected women with CD4 cell counts less than 350/μL (cumulative incidence = 2% [95% CI, 0%-7%]), one case in N=47 women with CD4 cell counts of 350 to 499/μL (cumulative incidence = 2% [95% CI, 0%-7%]), and seven cases in N=128 women with CD4 cell counts of 500/μL or greater (cumulative incidence = 6% [95% CI, 2%-10%]). One HIV-infected and one HIV-uninfected woman had CIN-3, but none had cancer.
The five-year cumulative incidence of HSIL+ and CIN-2+ was similar in HIV-infected women and HIV-uninfected women who were cytologically normal and oncogenic HPV-negative at enrollment.
There are several statistical methods for time-to-event analysis, among which is the Cox proportional hazards model that is most commonly used. However, when the absolute change in risk, instead of the risk ratio, is of primary interest or when the proportional hazard assumption for the Cox proportional hazards model is violated, an additive hazard regression model may be more appropriate. In this paper, we give an overview of this approach and then apply a semiparametric as well as a nonparametric additive model to a data set from a study of the natural history of human papillomavirus (HPV) in HIV-positive and HIV-negative women. The results from the semiparametric model indicated on average an additional 14 oncogenic HPV infections per 100 woman-years related to CD4 count < 200 relative to HIV-negative women, and those from the nonparametric additive model showed an additional 40 oncogenic HPV infections per 100 women over 5 years of followup, while the estimated hazard ratio in the Cox model was 3.82. Although the Cox model can provide a better understanding of the exposure disease association, the additive model is often more useful for public health planning and intervention.
The current study examined the relationship between cognitive function and falls in elders who did not meet criteria for dementia or Mild Cognitive Impairment (n=172). To address limitations of previous research, associations between cognitive function and falls controlled for the confounding effects of gait measures and other risk factors. A neuropsychological test battery was submitted to factor analysis yielding three orthogonal factors (verbal IQ, Speed/Executive Attention, Memory). Single and recurrent falls within the last 12 months were evaluated. We hypothesized that Speed/Executive Attention would be associated with falls. Additionally, we assessed whether associations between different cognitive functions and falls varied depending on whether single or recurrent falls were examined. Multivariate logistic regressions showed that worse scores on Speed/Executive Attention were associated with increased single and recurrent falls. Worse scores on Verbal IQ were related only to increased recurrent falls. Memory was not associated with either single or recurrent falls. These findings are relevant to risk assessment and prevention of falls, and point to possible shared neural substrate of cognitive and motor function.
cognition; falls; aging
Red meat consumption has been positively associated with colorectal cancer; however, the biologic mechanism underlying this relationship is not understood. Red meat is a major source of iron, which may play a role in colorectal carcinogenesis via increased crypt cell proliferation, cytotoxicity, and endogenous N-nitrosation. In a nested case-control study within the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, we prospectively evaluated multiple iron exposure parameters, including dietary intake and serum measures of iron, ferritin, transferrin, total iron binding capacity (TIBC), and unsaturated iron binding capacity (UIBC) in relation to incident colorectal adenoma in 356 cases and 396 matched, polyp-free controls. We also investigated variation in eight key genes involved in iron homeostasis in relation to colorectal adenoma in an additional series totaling 1,126 cases and 1,173 matched controls. We observed a positive association between red meat intake and colorectal adenoma (odds ratio comparing extreme quartiles [ORq4-q1] = 1.59, 95% confidence interval [CI]: 1.02-2.49, P-trend = 0.03). Serum TIBC and UIBC were inversely associated with colorectal adenoma (ORq4-q1 = 0.57, 95% CI: 0.37-0.88, P-trend = 0.03; and ORq4-q1 = 0.62, 95% CI: 0.40-0.95, P-trend = 0.04, respectively). Colorectal adenoma was not associated with serum ferritin, iron, or transferrin saturation, or with polymorphisms in genes involved in iron homeostasis. Serum TIBC and UIBC, parameters which have a reciprocal relationship with overall iron load, were inversely related to colorectal adenoma, suggesting that individuals with lower iron status have a reduced risk of colorectal adenoma.
Diet; meat; iron; colorectal; adenoma; cancer
HIV disease is associated with increased arterial stiffness, which may be related to inflammation provoked by HIV-related immune perturbation. We assessed the association of T cell markers of immune activation and immunosenescence with carotid artery stiffness among HIV-infected women.
Among 114 HIV-infected and 43 HIV-uninfected women, we measured CD4+ and CD8+ T cell populations expressing activation (CD38+HLA-DR+) and senescence (CD28-CD57+) markers. We then related these measures of immune status with parameters of carotid artery stiffness, including decreased distensibility, and increased Young’s elastic modulus, as assessed by B-mode ultrasound.
HIV infection was associated with increased CD4+ T cell activation, CD8+ T cell activation and CD8+ T cell senescence. Among HIV-infected women, adjusted for age, HIV medications, and vascular risk factors, higher CD4+CD38+HLA-DR+ T cell frequency was associated with decreased carotid artery distensibility (β= −2.00, 95% confidence interval [CI]= −3.86,−0.14, P=0.04) and increased Young’s modulus (β=1.00, 95% CI=0.03,1.97, P=0.04). These associations were affected little by further adjustment for CD4+ T cell count and viral load. Among HIV-infected women, higher frequencies of immunosenescent T cells, including CD4+CD28-CD57+ and CD8+CD28-CD57+ T cells, were also associated with decreased arterial distensibility. Among HIV-uninfected women, frequencies of activated or senescent T cells were not significantly associated with measures of carotid stiffness.
T cell activation and senescence are associated with arterial stiffness, suggesting that pro-inflammatory populations of T cells may produce functional or structural vascular changes in HIV-infected women.
To investigate the incidence of fear of falling (FOF) and the risk factors associated with transient versus persistent FOF in community-dwelling older adults.
Prospective cohort study.
Bronx County, New York.
Three hundred eighty participants without FOF at baseline in the Einstein Aging Study aged 70 and older.
FOF was assessed at baseline and during follow-up interviews at 2- to 3-month intervals for a minimum 2 years. Incident FOF was classified as transient or persistent FOF. Transient FOF was defined as new-onset FOF reported at only one interview, and persistent FOF was FOF reported at two or more interviews over a 2-year period.
Twenty-four-month cumulative incidence of incident FOF was 45.4%, with 60.0% of FOF being persistent. Predictors of incident FOF included female sex (adjusted hazard ratio (aHR) = 1.55, 95% confidence interval (CI) = 1.08–2.23), depressive symptoms (aHR = 1.16, 95% CI = 1.07–1.26), falls (aHR = 1.50, 95% CI = 1.01–2.21), and clinical gait abnormality (aHR = 2.07, 95% CI = 1.42–3.01). The proportion of participants with incident FOF increased linearly with increasing number of risk factors. Predictors for transient and persistent FOF were depressive symptoms and clinical gait abnormality. Female sex and previous falls were predictors of persistent but not transient FOF.
FOF status in older adults may change over time, with shared and distinct risk factors for persistent and transient FOF. Understanding the dynamic nature of FOF and these risk factors will help identify high-risk groups and design future intervention studies.
fear of falling; risk factors; older adults
Background. Human leukocyte antigen (HLA) class I and II genotype is associated with clearance of hepatitis C virus (HCV) infection, but little is known regarding its relation with HCV viral load or risk of liver disease in patients with persistent HCV infection.
Methods. High-resolution HLA class I and II genotyping was conducted in a prospective cohort of 519 human immunodeficiency virus (HIV)–seropositive and 100 HIV-seronegative women with persistent HCV infection. The end points were baseline HCV viral load and 2 noninvasive indexes of liver disease, fibrosis-4 (FIB-4), and the aspartate aminotransferase to platelet ratio index (APRI), measured at baseline and prospectively.
Results. DQB1*0301 was associated with low baseline HCV load (β = −.4; 95% confidence interval [CI], −.6 to −.3; P < .00001), as well as with low odds of FIB-4–defined (odds ratio [OR], .5; 95% CI, .2–.9; P = .02) and APRI-defined liver fibrosis (OR, .5; 95% CI, .3–1.0; P = .06) at baseline and/or during follow-up. Most additional associations with HCV viral load also involved HLA class II alleles. Additional associations with FIB-4 and APRI primarily involved class I alleles, for example, the relation of B*1503 with APRI-defined fibrosis had an OR of 2.0 (95% CI, 1.0–3.7; P = .04).
Conclusions. HLA genotype may influence HCV viral load and risk of liver disease, including DQB1*0301, which was associated with HCV clearance in prior studies.
There are conflicting data regarding the role of sex hormones in colorectal cancer development. Whereas clinical trials data indicate that hormone therapy use reduces the risk of colorectal cancer, data from prospective cohort studies suggest that circulating estrogen levels are positively associated with colorectal cancer risk. A surrogate measure of lifetime estrogen exposure is reproductive history. We investigated the relationship between reproductive factors and the risk of colorectal cancer.
Subjects were postmenopausal women enrolled in the National Institutes of Health–American Association of Retired Persons Diet and Health Study, a cohort of 214 162 individuals (aged 50–71 years) that included 2014 incident cases of colorectal cancer that occurred over a mean follow-up of 8.2 years. Questionnaires were used to collect data on reproductive factors, including ages at menarche, birth of first child, and menopause; parity, and use of oral contraceptives. Multivariable Cox proportional hazards models were constructed to examine associations between these reproductive factors and the risk of colorectal cancer, with adjustment for established colorectal cancer risk factors. All statistical tests were two-sided.
Age at menopause (≥55 vs <40 years: hazard ratio [HR] = 1.50, 95% confidence interval [CI] = 1.23 to 1.83; Ptrend = .008) and age at birth of first child (≥30 vs ≤19 years: HR = 1.26, 95% CI = 1.01 to 1.58; Ptrend = .05) were positively associated with the risk of colorectal cancer. Among women with no history of hormone therapy use, age at menarche (≥15 vs 11–12 years: HR = 0.73, 95% CI = 0.57 to 0.94; Ptrend = .02) and parity (≥5 children vs no children: HR = 0.80, 95% CI = 0.63 to 1.02; Ptrend = .10) were inversely associated with the risk of colorectal cancer.
These data support a role for sex hormones in colorectal tumorigenesis and suggest that greater endogenous estrogen exposure may increase the risk of colorectal cancer in postmenopausal women.
It is hypothesized that inflammation may mediate the relationship between obesity and endometrial cancer risk. We examined the associations of three inflammation markers, C-reactive protein (CRP), interleukin (IL)-6, and tumor necrosis factor (TNF)-α, with risk of endometrial cancer.
A case-cohort study was nested within the Women’s Health Initiative, a cohort of postmenopausal women. Baseline plasma samples of 151 incident endometrial cancer cases and 301 subcohort subjects not using hormones were assayed.
CRP, but not IL-6 or TNF-α, was positively associated with endometrial cancer risk after adjusting for age and BMI [hazard ratio comparing extreme quartiles (HRq4-q1) = 2.29; 95% confidence interval (CI) = 1.13–4.65; ptrend = 0.012). After additional adjustment for estradiol and insulin, this association was attenuated (HRq4-q1 = 1.70;95% CI= 0.78–3.68; ptrend = 0.127). Obesity (BMI ≥ 30 kg/m2) was associated with endometrial cancer risk in an age-adjusted model. The obesity effect was reduced by 48%, 67%, and 77% when either estradiol, CRP, or insulin, respectively, was included in the model, and it became null when all three factors were adjusted for simultaneously.
The association between inflammation, as indicated by a relatively high level of CRP, and endometrial cancer risk may partially be explained by hyperinsulinemia and elevated estradiol. Nevertheless, all three factors contribute to and mediate the link between obesity and endometrial cancer in postmenopausal women not using hormones.
The association between obesity and endometrial cancer risk in postmenopausal women may be attributed to inflammation, insulin resistance, and elevated estrogen.
While the human leukocyte antigen (HLA) genotype has been associated with the rate of HIV disease progression in untreated patients, little is known regarding these relationships in patients using highly active antiretroviral therapy (HAART). The limited data reported to date identified few HLA-HIV disease associations in patients using HAART and even occasional associations that were opposite of those found in untreated patients. We conducted high-resolution HLA class I and II genotyping in a random sample (n = 860) of HIV-seropositive women enrolled in a long-term cohort initiated in 1994. HLA-HIV disease associations before and after initiation of HAART were examined using multivariate analyses. In untreated HIV-seropositive patients, we observed many of the predicted associations, consistent with prior studies. For example, HLA-B*57 (β = −0.7; 95% confidence interval [CI] = −0.9 to −0.5; P = 5 × 10−11) and Bw4 (β = −0.2; 95% CI = −0.4 to −0.1; P = 0.009) were inversely associated with baseline HIV viral load, and B*57 was associated with a low risk of rapid CD4+ decline (odds ratio [OR] = 0.2; 95% CI = 0.1 to 0.6; P = 0.002). Conversely, in treated patients, the odds of a virological response to HAART were lower for B*57:01 (OR = 0.2; 95% CI = 0.0 to 0.9; P = 0.03), and Bw4 (OR = 0.4; 95% CI = 0.1 to 1.0; P = 0.04) was associated with low odds of an immunological response. The associations of HLA genotype with HIV disease are different and sometimes even opposite in treated and untreated patients.
Inflammation is hypothesized to play a role in colorectal tumorigenesis. Circulating levels of C-reactive protein (CRP), a serologic marker of the inflammatory response, have been positively associated with colorectal cancer development in some studies; however, there are limited data on the relation of CRP with colorectal adenomas, established precursors of colorectal cancer.
A nested case-control investigation of CRP levels and incident colorectal adenoma was conducted in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, a randomized trial of 154,942 individuals designed to test the efficacy of flexible sigmoidoscopy on colorectal cancer mortality when performed once, and then repeated 3-5 years later. Serum CRP levels were measured in baseline blood specimens from participants who were free of polyps in the left-sided colorectum at the baseline screening procedure, but who were found at the subsequent screen to have at least one colorectal adenoma(N=356), and in a set of polyp-free, frequency-matched controls(N=396).
In a multivariable logistic regression model that included established colorectal adenoma risk factors, a 1-unit increase in log CRP level was associated with a 15% reduction in risk of developing colorectal adenoma (OR=0.85, 95%CI, 0.75-0.98, Ptrend=0.01). This association did not differ according to body size, smoking behavior, gender, use of non-steroidal anti-inflammatory drugs, or adenoma location.
High circulating CRP levels may be protective against colorectal adenoma development.
Though at contrast with mechanistic data on inflammation and colorectal tumorigenesis, this finding is not inconsistent with prior results on CRP and colorectal adenoma and warrants further investigation.
Low insulin-like growth factor–1 (IGF-I) may influence the development of age-related cardiovascular diseases including congestive heart failure (CHF). Insulin-like growth factor binding protein-1 (IGFBP-1), which increases during catabolic states and inhibits anabolic IGF-I effects, is increased in CHF patients and has been associated prospectively with increased mortality among older adults and myocardial infarction survivors. We investigated the association between fasting plasma levels of IGF-I, IGFBP-1, IGFBP-3, and insulin and risk of incident CHF in the prospective Cardiovascular Health Study (CHS).
From among 5,888 65+ year-old adults in the Cardiovascular Health Study (CHS), we studied 566 incident CHF cases and 1,072 comparison subjects, after exclusion of underweight individuals (BMI < 18.5 kg/m2) and insulin users. Hazard ratios (HR) with 95% confidence intervals (CIs) for CHF were estimated after adjustment for age, race, gender, hypertension, systolic blood pressure, lipid levels, left ventricular hypertrophy, coronary disease, C-reactive protein, health status, diabetes, and BMI.
High baseline IGFBP-1 level was a significant predictor of CHF, independent of established CHF risk factors and inflammation markers. The HR per SD of IGFBP-1 was 1.22 (95% CI=1.07–1.39, p < 0.01). Relative to the lowest IGFBP-1 tertile, the HR was 1.29 (95% CI=0.96–1.74, p=0.09) for the second IGFBP-1 tertile and 1.47 (95% CI=1.06–2.04; p=0.02) for the highest IGFBP-1 tertile (tertile cutpoints 19.5 and 35.8 ng/ml). Total IGF-I, IGFBP-3, or insulin levels had no association with CHF after adjustment for CHF risk factors.
High circulating IGFBP-1 may be a CHF risk factor among older adults.
Presence of performance inconsistency during repeated assessments of gait may reflect underlying subclinical disease, and help shed light on the earliest stages of disablement. We studied inter-session fluctuations on three selected gait measures (velocity, stride length, and stride length variability) during normal pace walking as well as during a cognitively demanding ‘walking while talking’ condition using a repeated measurement burst design (six sessions within a 2-week period) in 71 nondisabled and nondemented community residing older adults, 40 with predisability (does activities of daily living unassisted but with difficulty). Subjects with predisability had slower gait velocity and shorter stride length on both the normal and walking while talking conditions at baseline compared to nondisabled subjects. However, there was no significant pattern of fluctuations across the six sessions on the three selected gait variables comparing the two groups during normal walking as well as on the walking while talking conditions. Our findings support consistency of gait measurements during the earliest stages of disability.
gait; elderly; measurement; variability; disability
While gait is widely used to assess health status in older adults, normative data is lacking. Our objective was to develop and compare norms for widely used gait parameters in adults age 70 and older using cross-sectional (conventional) and longitudinal (robust) approaches accounting for important confounders such as disease effects on gait.
Community-dwelling older adults (age>70, N=824) without dementia or disability
Eight quantitative gait parameters measured using an instrumented walkway.
Of the 824 subjects (conventional normal; CN sample), 304 were included in a ‘robust normal’ (RN) sample after excluding those with either prevalent or incident clinical gait abnormalities developing within one year of the baseline assessment to account for disease effects on gait performance. Descriptively, the RN sample showed better performance on all selected gait variables compared to the CN sample. For instance, mean gait velocity (± standard deviation) was 105.9±17.9 cm/sec in the RN sample compared to 93.3±23.2 cm/sec in the overall CN sample. Applying a one standard deviation below the mean (70.1 cm/sec) derived from CN sample to define slow gait, 15.9% (131) in overall cohort were classified as abnormal whereas the RN cut-off (88.0 cm/sec) classified 39.7% (327) in the overall cohort as abnormal.
Our findings suggest that cross-sectional conventional norms may under-estimate gait performance in aging. Longitudinal robust norms provide more accurate estimates of normal gait performance and thus may improve early detection of gait disorders in older adults.
gait; reference values; elderly
Obesity is a major risk factor for endometrial cancer, a relationship thought to be largely explained by the prevalence of high estrogen levels in obese women. Obesity is also associated with high levels of insulin, a known mitogen. However, no prospective studies have directly assessed whether insulin and/or insulin-like growth factor-I (IGF-I), a related hormone, are associated with endometrial cancer while accounting for estrogen levels. We therefore conducted a case-cohort study of incident endometrial cancer in the Women’s Health Initiative Observational Study, a prospective cohort of 93,676 postmenopausal women. The study involved all 250 incident cases and a random subcohort of 465 subjects for comparison. Insulin, total IGF-I, free IGF-I, IGF-binding protein-3, glucose, and estradiol levels were measured in fasting baseline serum specimens. Cox models were used to estimate associations with endometrial cancer, particularly endometrioid adenocarcinomas, the main histologic type (n = 205). Our data showed that insulin levels were positively associated with endometrioid adenocarcinoma [hazard ratio contrasting highest versus lowest quartile (HRq4-q1), 2.33; 95% confidence interval (95% CI), 1.13–4.82] among women not using hormone therapy after adjustment for age and estradiol. Free IGF-I was inversely associated with endometrioid adenocarcinoma (HRq4-q1, 0.53; 95% CI, 0.31–0.90) after adjustment for age, hormone therapy use, and estradiol. Both of these associations were stronger among overweight/obese women, especially the association between insulin and endometrioid adenocarcinoma (HRq4-q1, 4.30; 95% CI, 1.62–11.43). These data indicate that hyperinsulinemia may represent a risk factor for endometrioid adenocarcinoma that is independent of estradiol. Free IGF-I levels were inversely associated with endometrioid adenocarcinoma, consistent with prior cross-sectional data.
To determine predictors of treatment failure and recurrence after surgical excisional procedures for CIN in HIV-infected women.
A retrospective cohort study was conducted in which 136 eligible HIV-infected women treated for CIN between 1999 and 2005 were included. Data were abstracted from charts and computer databases. Treatment failures were defined as the presence of CIN 1+ at initial follow-up. Recurrences were defined as the presence of CIN 1+ subsequent to initial normal follow-up.
Treatment failure at initial follow-up was common, occurring in 51% of CIN 1 and 55% of CIN 2+. Most lesions detected at treatment failure were high grade (>70%), regardless of the grade of initial lesion. Significant risk factors for treatment failure were loop electrosurgical excision procedure (LEEP) compared to cold knife conization (RR=1.76; 95% CI: 1.15–2.64), and low CD4+ count (p = 0.04). Among those with an initial normal clinical evaluation, 55% eventually recurred. As with treatment failure, most lesions detected at recurrence were high grade. Risk factors for recurrence included use of LEEP (hazard ratio [HR] = 3.38; 95% CI: 1.55–7.39), higher HIV RNA level, and the presence of positive margins at treatment (HR = 6.12; 95% CI: 1.90–19.73).
Most CIN treatment of HIV-infected women studied either failed or resulted in recurrence. Of particular concern, many of these subsequent lesions were high grade. Conization, however, was associated with significantly less failure/recurrence than LEEP. Clinicians treating CIN in HIV-infected women should avoid raising expectations of cure and instead focus on the achievable goal of cancer prevention until there are better therapies for this patient population.
Cervical intraepithelial neoplasia; HIV; Cervical conization; Loop electrosurgical excision procedure; LEEP
frail; screening; gait; elderly
Studies of human leukocyte antigen (HLA) alleles and their relation with hepatitis C virus (HCV) viremia have had conflicting results. However, these studies have varied in size and methods, and few large studies assessed HLA class I alleles. Only one study conducted high resolution class I genotyping. The current investigation therefore involved high-resolution HLA class I and II genotyping of a large multi-racial cohort of US women with high prevalence of HCV and HIV. Our primary analyses evaluated associations between twelve HLA alleles identified through a critical review of the literature and HCV viremia in 758 HCV-seropositive women. Other alleles with >5% prevalence were also assessed; previously unreported associations were corrected for multiple comparisons. DRB1*0101 (prevalence ratio [PR] = 1.7; 95% confidence interval [CI] = 1.1–2.6), B*5701 (PR=2.0; 95% CI = 1.0–3.1), B*5703 (PR = 1.7; 95% CI = 1.0–2.5), and Cw*0102 (PR = 1.9; 95% CI = 1.0–3.0) were associated with the absence of HCV RNA (i.e., HCV clearance), while DRB1*0301 (PR = 0.4; 95% CI = 0.2–0.7) was associated with HCV RNA positivity. DQB1*0301 was also associated with the absence of HCV RNA but only among HIV-seronegative women (PR = 3.4; 95% CI = 1.2–11.8). Each of these associations was among those predicted. We additionally studied the relation of HLA alleles with HCV infection (serostatus) in women at high risk of HCV from injection drug use (IDU; N=838), but no significant relationships were observed.
HLA genotype influences host capacity to clear HCV viremia. The specific HLA associations observed in the current study are unlikely to be due to chance since they were a priori hypothesized.
human leukocyte antigen; HIV; injection drug user; multiple comparisons; killer immunoglobulin-like receptor