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1.  Fracture Risk in Older, Long-term Survivors of Early-Stage Breast Cancer 
Breast cancer survivorship has increased and the association of long-term bone health with breast cancer and its treatment is unclear. This issue is important for older women who face an increased risk of osteoporotic fracture-related morbidity and mortality.
To examine the effect of breast cancer and its treatment on fracture risk in older breast cancer survivors and non-breast cancer comparisons.
A 10-year prospective cohort study beginning 5 years after a diagnosis of breast cancer for survivors and match date for comparison women.
The study was conducted within six integrated health care systems.
Women 65 years and older who were alive and recurrence free 5 years after a diagnosis of early-stage breast cancer and matched on age, study site, and enrollment year to a non-breast cancer comparison cohort.
Cox proportional hazards models were used to estimate the association between fracture risk and survivor-comparison status, adjusting for drugs and risk factors associated with bone health. A subanalysis was conducted to evaluate the association between tamoxifen exposure and fracture risk.
Our analysis included 1,286 survivors and 1,286 comparison women with a mean age of 77.7 years in both groups. Survivor and comparison women were predominantly white and non-Hispanic, 81.6% and 85.2%, respectively. We observed no difference in fracture rates between groups (HR=1.1; 95%CI 0.9, 1.3). The protective effect of tamoxifen was not statistically significant (HR=0.9; 95%CI 0.6, 1.2).
Our findings suggest long-term survivors of early stage breast cancer diagnosed at age 65 and older are not at increased risk of osteoporotic fractures compared to age-matched non-breast cancer women. There appears to be no long-term protection from fractures following tamoxifen use.
PMCID: PMC3686911  PMID: 23647433
Osteoporotic fractures; breast cancer survivors; postmenopausal women; cohort study; pharmacoepidemiology
2.  Neighborhood Socioeconomic Status and Use of Colonoscopy in an Insured Population – A Retrospective Cohort Study 
PLoS ONE  2012;7(5):e36392.
Low-socioeconomic status (SES) is associated with a higher colorectal cancer (CRC) incidence and mortality. Screening with colonoscopy, the most commonly used test in the US, has been shown to reduce the risk of death from CRC. This study examined if, among insured persons receiving care in integrated healthcare delivery systems, differences exist in colonoscopy use according to neighborhood SES.
We assembled a retrospective cohort of 100,566 men and women, 50–74 years old, who had been enrolled in one of three US health plans for ≥1 year on January 1, 2000. Subjects were followed until the date of first colonoscopy, date of disenrollment from the health plan, or December 31, 2007, whichever occurred first. We obtained data on colonoscopy use from administrative records. We defined screening colonoscopy as an examination that was not preceded by gastrointestinal conditions in the prior 6-month period. Neighborhood SES was measured using the percentage of households in each subject's census-tract with an income below 1999 federal poverty levels based on 2000 US census data. Analyses, adjusted for demographics and comorbidity index, were performed using Weibull regression models.
The average age of the cohort was 60 years and 52.7% were female. During 449,738 person-years of follow-up, fewer subjects in the lowest SES quartile (Q1) compared to the highest quartile (Q4) had any colonoscopy (26.7% vs. 37.1%) or a screening colonoscopy (7.6% vs. 13.3%). In regression analyses, compared to Q4, subjects in Q1 were 16% (adjusted HR = 0.84, 95% CI: 0.80–0.88) less likely to undergo any colonoscopy and 30%(adjusted HR = 0.70, CI: 0.65–0.75) less likely to undergo a screening colonoscopy.
People in lower-SES neighborhoods are less likely to undergo a colonoscopy, even among insured subjects receiving care in integrated healthcare systems. Removing health insurance barriers alone is unlikely to eliminate disparities in colonoscopy use.
PMCID: PMC3342210  PMID: 22567154
3.  Adherence and Occurrence of Fractures after Switching to Once-Monthly Oral Bisphophonates 
Pharmacoepidemiology and drug safety  2010;19(12):1233-1240.
Reducing dosing demands of medications generally increases adherence, although this relationship has not been demonstrated with the once-monthly oral bisphosphonates (BP). The study aim is to test whether switching from once-weekly BPs to once-monthly BPs improves adherence and fracture risk.
This is an interrupted times-series analysis of new users of once-weekly BPs in a nationwide administrative health database from 2003–2007. Participants include 1835 individuals who switched to once-monthly BPs and two propensity-matched comparator groups: 1835 individuals who switched to a different once-weekly BP, and 1835 who did not switch. We measured changes in adequate adherence pre- and post-switch as monthly medication possession ratio >0.80, and calculated incidence rate ratios [IRR] of osteoporotic fractures.
All study groups experienced major adherence failure in the first year of therapy: the proportion of adequate adherers was 42% among once-monthly switchers, 47% among once-weekly switchers, and 37% among nonswitchers. However, the once-monthly switch was associated with less adherence failure (4% fewer adherers per month pre-switch vs. 1% fewer adherers per month post-switch, p<.000). There was no statistically significant change in adherence rates for the other groups. We did not detect significantly reduced fracture risk with once-monthly switch: 1 year post-switch, the fracture incidence risk ratios for once-monthly switchers relative to once-weekly switchers were IRR 0.83, 95% CI: 0.50–1.36, and IRR 0.90, 95% CI: 0.54–1.49, relative to nonswitchers).
Reducing the dosing demands of oral bisphosphonates from once-weekly to once-monthly decreased adherence failure but had an uncertain impact on fracture risk.
PMCID: PMC3079953  PMID: 21108489
patient compliance; bisphosphonates; osteoporosis; osteoporotic fractures; medication adherence
4.  Out-of-Pocket Burden of Health Care Spending and the Adequacy of the Medicare Part D Low-Income Subsidy 
Medical care  2010;48(6):503-509.
Little is known about how much Medicare families can afford to pay for health care and whether the Medicare prescription drug program (Part D) will provide financial protection. In this paper we assess total out-of-pocket health care spending of Medicare families in the context of their available resources in the year prior to Part D. We find that high health spending burdens are common. Medicare families with incomes up to 250% of the Federal Poverty Level are at high risk for incurring burdensome health care costs, and this includes many who would not be eligible for Part D Low-income subsidy assistance.
PMCID: PMC3084515  PMID: 20473197
5.  Medicare Part D’s Exclusion of Benzodiazepines and Fracture Risk in Nursing Homes 
Archives of internal medicine  2010;170(8):693-698.
Medicare Part D excludes benzodiazepines from coverage and some state Medicaid programs also limit coverage. We assessed whether such policies decrease the risk of fractures in the elderly living in nursing homes.
This is a quasi-experimental study with interrupted time-series estimation and extended Cox proportional hazards models comparing changes in outcomes pre- and post-Part D in a nationwide sample of nursing home residents in 48 states. The study included 1,068,104 residents and a subsample of 50,874 residents with fracture data from one pharmacy provider. We assessed monthly prescribing rates of benzodiazepines and potential substitutes over the period 2005- June 2007, and hazard ratios for incident hip fracture and falls, adjusted for age, sex, and race. Estimates were stratified by concurrent Medicaid limits on benzodiazepines: no coverage (n=1 state) or partial coverage (n=6 states), versus complete coverage (n=41 states).
The no coverage policy resulted in an immediate and significant reduction of 10 absolute points in benzodiazepine use (27% to 17%) after Part D (95% confidence interval [CI]: −.11- −.09, p<.0001). Benzodiazepine use remained stable in the partial and complete coverage states. Hazard ratios for incident hip fracture were 1.60 (95% CI: 1.05-2.45, p=.030) in the no coverage state after Part D, and 1.17 (95% CI: 0.93-1.46, p=.179) in the partial coverage states, relative to complete coverage states.
This study found that drug coverage exclusion policies affect the medication use of nursing home residents and may not decrease their fracture risk.
PMCID: PMC2907144  PMID: 20421554
6.  Adoption of Once-monthly Oral Bisphosphonates and the Impact on Adherence 
The American journal of medicine  2010;123(3):275-280.
The extent of the adoption of once-monthly bisphosphonates into general clinical practice is not known, nor is it known if the novel formulation improves adherence.
We analyzed administrative claims 2003-2006 from a large employer-based health insurance database for incident use of oral bisphosphonates and stratified users by daily, weekly and monthly dosing regimen. We measured adherence as the medication possession ratio (MPR) during the first year of therapy. We compared patient characteristics by dosing regimen and evaluated how the dosing regimen influenced the MPR.
We identified 61,125 incident users of bisphosphonates (n=1034 daily, n=56,925 weekly, n=3166 monthly). Monthly bisphosphonate users were, on average, slightly older than the other groups (mean age 66 years monthly vs. 65 weekly or 66 daily, p<.05.) and more often lived in the U.S. North Central or South (76% vs. 72% weekly or 69% daily users, p<.05). There were no detectable differences among the dosing groups in the history of serious GI risk, comorbidity burden, or prior osteoporotic fractures. During the first year of bisphosphonate therapy, 49% of monthly users had MPR ≥80% compared to 49% weekly users (N.S.) or 23% daily users (p<.0001).
We found little evidence of preferential prescribing of monthly bisphosphonates to certain types of patients. Furthermore, we found no evidence of improved bisphosphonate adherence with monthly dosing relative to weekly dosing, although adherence with either weekly or monthly dosing was significantly better than with daily dosing.
PMCID: PMC2831769  PMID: 20193837
patient compliance; bisphosphonates; novel formulation
7.  Adherence with tobramycin inhaled solution and health care utilization 
Adherence with tobramycin inhalation solution (TIS) during routine cystic fibrosis (CF) care may differ from recommended guidelines and affect health care utilization.
We analyzed 2001-2006 healthcare claims data from 45 large employers. Study subjects had diagnoses of CF and at least 1 prescription for TIS. We measured adherence as the number of TIS therapy cycles completed during the year and categorized overall adherence as: low ≤ 2 cycles, medium >2 to <4 cycles, and high ≥ 4 cycles per year. Interquartile ranges (IQR) were created for health care utilization and logistic regression analysis of hospitalization risk was conducted by TIS adherence categories.
Among 804 individuals identified with CF and a prescription for TIS, only 7% (n = 54) received ≥ 4 cycles of TIS per year. High adherence with TIS was associated with a decreased risk of hospitalization when compared to individuals receiving ≤ 2 cycles (adjusted odds ratio 0.40; 95% confidence interval 0.19-0.84). High adherence with TIS was also associated with lower outpatient service costs (IQR: $2,159-$8444 vs. $2,410-$14,423) and higher outpatient prescription drug costs (IQR: $35,125-$60,969 vs. $10,353-$46,768).
Use of TIS did not reflect recommended guidelines and may impact other health care utilization.
PMCID: PMC3033861  PMID: 21251275
8.  The Dynamics of Chronic Gout Treatment: medication gaps and return to therapy 
To identify gaps in therapy with urate-lowering drugs for the treatment of gout as well as factors associated with resuming therapy.
We identified persons from two integrated delivery systems 18 years or older with a diagnosis of gout who initiated use of a urate-lowering drug from January 1, 2000 through June 30, 2006 and who had a gap in therapy. A gap was defined as a period of over 60 days after the completion of one prescription in which no refill for a urate-lowering drug was obtained. Survival curves were used to assess return to therapy of urate-lowering drugs. Cox proportional hazards analysis estimated the association between covariates and return to therapy.
There were 4,166 new users of urate-lowering drugs (97% received allopurinol) of whom 2,929 (70%) had a gap in therapy. Among those with a gap, in 75% it occurred in the first year of therapy. Fifty percent of patients with a gap returned to therapy within 8 months, and by 4 years it was 75%. Age 45 to 74 (<45 referent) and greater duration of urate-lowering drug use prior to the gap was associated with resuming treatment within one year. In contrast, receipt of NSAIDs or glucocorticoids in the year prior to the gap was associated with a reduced likelihood of resuming therapy.
The majority of gout patients with gaps in urate-lowering drug use returned to treatment. More investigation is needed to better understand why patients may go for months without refilling prescriptions given the clinical consequences of nonadherence.
PMCID: PMC2813203  PMID: 20102992
persistence; adherence; compliance; gout; urate lowering drugs
9.  Nursing Home Residents and Enrollment in Medicare Part D 
to assess the impact of Medicare Part D in the nursing home (NH) setting.
a population-based study using 2005–2006 prescription dispensing records, Poisson regressions with generalized estimating equations, and interrupted times series estimation with segmented regression methods.
a nationwide sample of long-stay Medicare enrollees in NHs (n=861,082)
probability of Part D enrollment, changes in source of drug payments, changes in average number of monthly prescriptions dispensed per resident.
In 2006, 81% of NH residents enrolled in Part D, 16% had other drug coverage, and 3% (n=11,000) remained without drug coverage, which was the same rate of no drug coverage as in 2005. NH residents who did not enroll in Part D were the oldest old (RR 0.82, p<.000), had no drug coverage in 2005 (RR 0.84, p<.001), and had high comorbidity burden (RR 0.94, p<.000). The proportion of prescription drugs paid out-of-pocket decreased from 11% in 2005 to 8% in 2006 (p<.001). Average monthly prescription use per resident in 2006 decreased by half a prescription relative to 2005 levels (9.6 scripts vs. 10.1 scripts, p<.003).
Part D decreased some out-of-pocket drug costs, but did not expand drug coverage in the NH population or reach some vulnerable segments. Part D was also associated with some disruption in NH drug use, especially right after implementation.
PMCID: PMC2893584  PMID: 19702612
Medicare; prescription drugs; nursing home
10.  Medication Adherence and the Use of Generic Drug Therapies 
to assess if the lower copayments often charged for generic drugs explains the improved drug adherence associated with use of generic drugs.
We analyzed 2001–2004 healthcare claims data from 45 large employers. Study subjects were aged 18 years +, had 1 or more of 5 study conditions (hypercholesterolemia, hypertension, hypothyroidism, seizure disorders, and type 2 diabetes), and new use of generic-only or brand-only drug therapy for that condition. We measured adherence as the medication possession ratio (MPR), and adequate adherence as MPR >= 80%. Logistic regressions were conducted to assess adequate adherence adjusting for copayments.
We identified 327,629 new users of drug therapy for the study conditions. Proportion of individuals starting generic therapies ranged from 9% in hypothyroidism to 45% in hypertension. After 1 year of therapy, 66.2% of individuals with hypothyroidism achieved MPR >= 80% compared to 53.4% with hypertension, 53.2% with hypercholesterolemia, 52.0% with diabetes, and 42.2% with seizure disorders. Logistic regressions of adequate adherence showed generics were associated with higher adherence relative to brands in 2 conditions (hypercholesterolemia AOR 1.52, 95% CI: 1.44–1.60; diabetes AOR 1.06, 95% CI: 1.01–1.12, p<.05), with lower adherence in 2 conditions (hypertension AOR 0.75, 95% CI:.73-.77; hypothyroidism AOR 0.86, 95% CI:.78-.94, p<.05), and no difference in seizure disorders. In comparison, the likelihood of achieving MPR >= 80% with $0 copayments relative to $1-$9 ranged from AOR 1.32 for seizure disorders (95% CI: 1.41–1.43) to AOR 1.45 for hypothyroidism (95% CI: 1.43–1.48).
Generic prescribing was associated with improved medication adherence in 2 of 5 study conditions, and the effect was modest. Copayments of $0 were associated with improved adherence across all study conditions.
PMCID: PMC2918380  PMID: 19589012
adherence; type 2 diabetes; hypertension; hypercholesterolemia; hypothyroidism; and seizure disorders
11.  Comparison of Drug Adherence Rates Among Patients with Seven Different Medical Conditions 
Pharmacotherapy  2008;28(4):437-443.
Study Objective
To compare drug adherence rates among patients with gout, hypercholesterolemia, hypertension, hypothyroidism, osteoporosis, seizure disorders, and type 2 diabetes mellitus by using a standardized approach.
Longitudinal study.
Data Source
Health care claims data from 2001–2004.
A total of 706,032 adults aged 18 years or older with at least one of the seven medical conditions and with incident use of drug therapy for that condition.
Measurements and Main Results
Drug adherence was measured as the sum of the days’ supply of drug therapy over the first year observed. Covariates were age, sex, geographic residence, type of health plan, and a comorbidity score calculated by using the Hierarchical Condition Categories risk adjuster. Bivariate statistics and stratification analyses were used to assess unadjusted means and frequency distributions. Sample sizes ranged from 4984 subjects for seizure disorders to 457,395 for hypertension. During the first year of drug therapy, 72.3% of individuals with hypertension achieved adherence rates of 80% or better compared with 68.4%, 65.4%, 60.8%, 54.6%, 51.2%, or 36.8% for those with hypothyroidism, type 2 diabetes, seizure disorders, hypercholesterolemia, osteoporosis, or gout, respectively. Age younger than 60 years was associated with lower adherence across all diseases except seizure disorders. Comorbidity burden and adherence varied by disease. As comorbidity increased, adherence among subjects with osteoporosis decreased, whereas adherence among those with hypertension, hypercholesterolemia, or gout increased. Add-on drug therapies and previous experience with taking drugs for the condition increased adherence among subjects with hypertension, type 2 diabetes, hypothyroidism, or seizure disorders but not the other conditions.
This uniform comparison of drug adherence revealed modest variation across six of seven diseases, with the outlier condition being gout.
PMCID: PMC2737273  PMID: 18363527
drug adherence; comparative study; type 2 diabetes mellitus; hypertension; osteoporosis; hypercholesterolemia; gout; hypothyroidism; seizure disorders
12.  Adherence with urate-lowering therapies for the treatment of gout 
Adherence to urate-lowering drugs (ULDs) has not been well evaluated among those with gout. Our aim was to assess the level and determinants of non-adherence with ULDs prescribed for gout.
We identified persons using two integrated delivery systems aged 18 years or older with a diagnosis of gout who initiated use of allopurinol, probenecid or sulfinpyrazone from 1 January 2000 to 30 June 2006. Non-adherence was measured using the medication possession ratio (MPR) over the first year of therapy and defined as an MPR < 0.8. Descriptive statistics were calculated and logistic regression was used to estimate the strength of the association between patient characteristics and non-adherence.
A total of 4,166 gout patients initiated ULDs; 97% received allopurinol. Median MPR for any ULD use was 0.68 (interquartile range (IQR) 0.64). Over half of the patients (56%) were non-adherent (MPR < 0.8). In adjusted analyses, predictors of poor adherence included younger age (odds ratio (OR) 2.43, 95% confidence interval (CI) 1.86 to 3.18 for ages <45 and OR 1.44, 95% CI 1.08 to 1.93 for ages 45 to 49), fewer comorbid conditions (OR 1.46, 95% CI 1.20 to 1.77), no provider visits for gout prior to urate-lowering drug initiation (OR 1.28, 95% CI 1.05 to 1.55), and use of non-steroidal anti-inflammatory drugs in the year prior to urate-lowering drug initiation (OR 1.15, 95% CI 1.00 to 1.31).
Non-adherence amongst gout patients initiating ULDs is exceedingly common, particularly in younger patients with less comorbidity and no provider visits for gout prior to ULD initiation. Providers should be aware of the magnitude of non-adherence with ULDs.
PMCID: PMC2688196  PMID: 19327147

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