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1.  The insulin-like growth factor axis and risk of liver disease in hepatitis C virus/HIV-co-infected women 
AIDS (London, England)  2008;22(4):527-531.
Insulin-like growth factor (IGF) I stimulates the proliferation of hepatic stellate cells (HSC), the primary source of extracellular matrix accumulation in liver fibrosis. In contrast, insulin-like growth factor binding protein (IGFBP) 3, the most abundant IGFBP in circulation, negatively modulates HSC mitogenesis. To investigate the role of the IGF axis in hepatitis C virus (HCV)-related liver disease among high-risk patients, we prospectively evaluated HCV-viremic/HIV-positive women.
A cohort investigation.
Total IGF-I and IGFBP-3 were measured in baseline serum specimens obtained from 472 HCV-viremic/HIV-positive subjects enrolled in the Women's Inter-agency HIV Study, a large multi-institutional cohort. The aspartate aminotransferase to platelet ratio index (APRI), a marker of liver fibrosis, was assessed annually.
Normal APRI levels (< 1.0) at baseline were detected in 374 of the 472 HCV-viremic/HIV-positive subjects tested, of whom 302 had complete liver function test data and were studied. IGF-I was positively associated [adjusted odds ratio comparing the highest and lowest quartiles (AORq4–q1), 5.83; 95% confidence interval (CI) 1.17–29.1; Ptrend = 0.03], and IGFBP-3 was inversely associated (AORq4–q1, 0.13; 95% CI 0.02–0.76; Ptrend = 0.04), with subsequent (incident) detection of an elevated APRI level(> 1.5), after adjustment for the CD4 T-cell count, alcohol consumption, and other risk factors.
High IGF-I may be associated with increased risk and high IGFBP-3 with reduced risk of liver disease among HCV-viremic/HIV-positive women.
PMCID: PMC3507535  PMID: 18301066
aspartate aminotransferase to platelet ratio index; APRI; hepatitis C virus (HCV); HIV; IGFBP-3; IGF; liver disease
2.  The Relation of HLA Genotype to Hepatitis C Viral Load and Markers of Liver Fibrosis in HIV-Infected and HIV-Uninfected Women 
The Journal of Infectious Diseases  2011;203(12):1807-1814.
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.
PMCID: PMC3100515  PMID: 21606539
3.  Human Leukocyte Antigen Genotype and Risk of HIV Disease Progression before and after Initiation of Antiretroviral Therapy▿‡ 
Journal of Virology  2011;85(20):10826-10833.
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.
PMCID: PMC3187522  PMID: 21849458
4.  Associations of Insulin-Like Growth Factor (IGF)–I and IGF-Binding Protein–3 with HIV Disease Progression in Women 
The Journal of infectious diseases  2008;197(2):319-327.
The insulin-like growth factor (IGF) axis has been hypothesized to influence the rate of human immunodeficiency virus (HIV) disease progression. This premise is based largely on laboratory models showing that IGF-I stimulates thymic growth and increases lymphocyte numbers and that IGF-binding protein (IGFBP)–3 has an opposing effect, inhibiting hematopoietic stem cell development.
We studied 1422 HIV-infected women enrolled in a large cohort that entailed semiannual follow-up (initiated in 1994). Baseline serum samples were tested for IGF-I and IGFBP-3 to determine their associations with incident clinical acquired immunodeficiency syndrome (AIDS) and CD4+ T cell count decline prior to April 1996 (before the era of highly active antiretroviral therapy [HAART]).
Low IGF-I levels (Ptrend = .02) and high IGFBP-3 levels (Ptrend = .02) were associated with rapid CD4+ T cell count decline. Only IGFBP-3, however, was significantly associated with AIDS incidence (hazard ratio for highest vs. lowest quartile, 2.65 [95% confidence interval, 1.30–5.42]; Ptrend = .02) in multivariable models.
These findings suggest that serum levels of IGFBP-3 (and possibly IGF-I) are associated with the rate of HIV disease progression in women and, more broadly, that interindividual heterogeneity in the IGF axis may influence HIV pathogenesis. If correct, the IGF axis could be a target for interventions to slow HIV disease progression and extend the time before use of HAART becomes necessary.
PMCID: PMC3127259  PMID: 18177247
5.  Specific HLA Class I and II Alleles Associated with Hepatitis C Virus Viremia 
Hepatology (Baltimore, Md.)  2010;51(5):1514-1522.
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.
PMCID: PMC2946382  PMID: 20169624
human leukocyte antigen; HIV; injection drug user; multiple comparisons; killer immunoglobulin-like receptor
6.  Marginal and Mixed Effects Models in the Analysis of HPV Natural History Data 
Human papillomavirus (HPV) natural history has several characteristics that, at least from a statistical perspective, are not often encountered elsewhere in infectious disease and cancer research. There are, for example, multiple HPV types, and infection by each HPV type may be considered separate events. While concurrent infections are common, the prevalence, incidence, duration/persistence of each individual HPV can be separately measured. However, repeated measures involving the same subject tend to be correlated. The probability of detecting any given HPV type, for example, is greater among individuals who are currently positive for at least one other HPV type. Serial testing for HPV over time represents a second form of repeated measures. Statistical inferences that fail to take these correlations into account would be invalid. However, methods that do not use all the data would be inefficient. Marginal and mixed effects models can address these issues, but are not frequently utilized in HPV research. The current paper provides an overview of these methods, and then uses HPV data from a cohort of HIV-positive women to illustrate how they may be applied, and compare their results. The findings show the greater efficiency of these models compared with standard logistic regression and Cox models. Because mixed effects models estimate subject-specific associations, they sometimes gave much higher effect estimates than marginal models, which estimate population-averaged associations. Overall, the results demonstrate that marginal and mixed effects models are efficient for studying HPV natural history, but also highlight the importance of understanding how these models differ.
PMCID: PMC2839537  PMID: 20056635
statistical methods; cervical neoplasia; human papillomavirus; HPV; HIV; frailty models; mixed effects models; WLW models; frailty models

Results 1-6 (6)