Stephen S Johnston

Truven Health Analytics, Ann Arbor, Michigan, United States

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Publications (50)122.46 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Objectives To compare antiretroviral therapy (ART) adherence and persistence and total healthcare expenditures in Medicaid-insured patients with human immunodeficiency virus (HIV) initiating preferred or nonpreferred first-line ART based on March 2012 HHS HIV treatment guidelines. Study Design Retrospective observational study using Medicaid administrative healthcare claims from 15 states. Methods Subjects were HIV patients 18 to 64 years who initiated first-line HIV-related ART between January 1, 2007, and September 30, 2011, with continuous enrollment for 6 months prior to and at least 3 months following ART initiation. Patients were classified as having initiated preferred or nonpreferred ART based on March 2012 HHS HIV treatment guidelines. Outcomes were: ART adherence (proportion of days covered dichotomized at ≥80% and ≥95%), time to ART nonpersistence, and per patient per month (PPPM) total healthcare expenditures. Outcomes were evaluated using multivariable regressions. Results Sample included 1979 patients initiating preferred ART regimens and 1614 patients initiating nonpreferred ART; overall mean age was 41 years; 48% of subjects were female. In the multivariable analyses, patients initiating preferred ART regimens had significantly greater odds of adherence ≥80% (odds ratio [OR], 1.38; 95% CI, 1.07-1.77) and adherence ≥95% (OR, 1.26; 95% CI, 1.05-1.51), and a significantly lower hazard of nonpersistence (HR, 0.48; 95% CI, 0.44-0.52). PPPM total healthcare expenditures were numerically lower for patients initiating preferred ART regimens (-$341; 95% CI, -$888 to $255) but the difference was not deemed significant. Conclusions This study reinforces the value of HHS recommendations for first-line ART. The potential impact of these findings will grow as more HIV patients become Medicaid-eligible under the Patient Protection and Affordable Care Act.
    The American journal of managed care. 06/2014; 20(6):448-455.
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    ABSTRACT: Hip fractures are common, morbid, costly, and associated with subsequent fractures. Historically, post-fracture osteoporosis medication use rates have been poor, but have not been recently examined in a large-scale study. We conducted a retrospective, observational cohort study based on U.S. administrative insurance claims data for beneficiaries with commercial or Medicare supplemental health insurance. Eligible participants were hospitalized for hip fracture between January 1, 2002, and December 31, 2011, and aged 50 years or older at admission. The outcome of interest was osteoporosis medication use within 12 months after discharge. Patients were censored after 12 months, loss to follow-up, or a medical claim for cancer or Paget's disease, whichever event occurred first. During the study period, 96,887 beneficiaries met inclusion criteria, with a mean age 80 years and 70% were female. A total of 34,389 (35.5%) patients were censored before reaching 12 months of follow-up. The Kaplan-Meier estimated probability of osteoporosis medication use within 12 months after discharge was 28.5%. The rates declined significantly from 40.2% in 2002, to 20.5% in 2011 (P for trend < 0.001). In multivariable Cox proportional hazards models, a number of patient characteristics were associated with reduced likelihood of osteoporosis medication use, including older age and male gender. However, the predictor most strongly and most positively associated with osteoporosis medication use after fracture was osteoporosis medication use before the fracture (Hazard Ratio = 7.45, 95% CI 7.23-7.69). Most patients suffering a hip fracture do not use osteoporosis medication in the subsequent year and treatment rates have worsened. © 2014 American Society for Bone and Mineral Research.
    Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 02/2014; · 6.04 Impact Factor
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    ABSTRACT: To describe the characteristics, treatment, and health care expenditures of Medicare Supplemental-insured patients with painful diabetic peripheral neuropathy (pDPN), post-herpetic neuralgia (PHN), or fibromyalgia. Retrospective cohort study. United States clinical practice, as reflected within a database comprising administrative claims from 2.3 million older adults participating in Medicare supplemental insurance programs. Selected patients were aged ≥65 years, continuously enrolled in medical and prescription benefits throughout years 2008 and 2009, and had ≥1 medical claim with an International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis code for DPN, PHN, or fibromyalgia, followed within 60 days by a medication or pain intervention procedure used in treating pDPN, PHN, or fibromyalgia during 2008-2009. Utilization of, and expenditures on, pain-related and all-cause pharmacotherapy and medical interventions in 2009. The study included 25,716 patients with pDPN (mean age 75.2 years, 51.2% female), 4,712 patients with PHN (mean age 77.7 years, 63.9% female), and 25,246 patients with fibromyalgia (mean age 74.4 years, 73.0% female). Patients typically had numerous comorbidities, and many were treated with polypharmacy. Mean annual expenditures on total pain-related health care and total all-cause health care, respectively, (in 2010 USD) were: $1,632, $24,740 for pDPN; $1,403, $16,579 for PHN; and $1,635, $18,320 for fibromyalgia. In age-stratified analyses, pain-related health care expenditures decreased as age increased. The numerous comorbidities, polypharmacy, and magnitude of expenditures in this sample of Medicare supplemental-insured patients with pDPN, PHN, or fibromyalgia underscore the complexity and importance of appropriate management of these chronic pain patients.
    Pain Medicine 01/2014; · 2.46 Impact Factor
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    ABSTRACT: To quantify the prevalence of potential drug-drug/drug-condition interactions (DDI/DCI) among fibromyalgia patients initiating pregabalin or duloxetine, and to determine the impact of potential DDI/DCI on health care expenditures. Retrospective cohort study. U.S. clinical practice, as reflected within a large administrative claims database. Fibromyalgia patients newly initiating pregabalin or duloxetine between July 1, 2008 and October 1, 2010 (initiation date = index). Potential DDI measured using clinical software that identifies co-prescription of medications that potentially interact with pregabalin or duloxetine. Potential DCI, drawn from the contraindications and warnings and precautions sections of pregabalin and duloxetine prescribing information, measured using administrative claims-based algorithms. All-cause health care expenditures measured throughout a 6-month postindex period. Analyses included univariate, bivariate, and multivariable statistical approaches. Seven thousand seven hundred fifty-one pregabalin and 7,785 duloxetine initiators were selected for study: mean age 49 years, 88% female. Only 1.4% of pregabalin initiators had ≥1 potential pregabalin DCI; none had potential pregabalin DDI. In contrast, 67% of duloxetine initiators had potential duloxetine DDI/DCI, driven mostly by potential duloxetine DDI (62% of duloxetine initiators). Compared between pregabalin and duloxetine initiators, differences in the prevalence of potential DDI/DCI were statistically significant (P < 0.001). Multivariable analyses indicated that, among duloxetine initiators, those with potential duloxetine DDI/DCI had postinitiation health care expenditures that were $670 higher (P < 0.001) than those without potential duloxetine DDI/DCI. Among pregabalin initiators, potential pregabalin DDI/DCI were not associated with health care expenditures. Among fibromyalgia patients initiating pregabalin or duloxetine, potential duloxetine DDI could be highly prevalent. Among duloxetine initiators, potential duloxetine DDI/DCI were significantly associated with increased health care expenditures.
    Pain Medicine 01/2014; · 2.46 Impact Factor
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    ABSTRACT: This study examined the association between teriparatide (TPTD) adherence, and healthcare utilization and costs among hip fracture (HFx) patients. Individuals aged 50years and older with an HFx between 1/1/2002-12/31/2010 were identified from a large US administrative claims database. The first HFx date during this period was designated as the index. Selected patients had at least 6months of pre-index continuous enrollment (baseline) and no baseline TPTD use, cancer, or Paget's disease. Patients initiating TPTD post-index were followed until censoring at switch to bisphosphonates, disenrollment, 36months post-index, or diagnosis of cancer or Paget's disease. Teriparatide adherence was measured as the proportion of days covered (PDC) by TPTD prescriptions, during the follow-up period, to construct three adherence groups: low (PDC≤0.5), medium (0.5<PDC≤0.8), and high (PDC>0.8) adherence. Outcome measures were repeated HFx, number of inpatient admissions, and per-patient-per-month (PPPM) healthcare costs. Multivariable generalized linear models examined the association between the TPTD adherence groups and the outcomes, adjusting for cross-group differences in patient characteristics. A total of 824 patients (mean age 75years, 90% female) were included: 30% low, 27% medium, and 44% high adherence. In multivariable analyses, high adherence was significantly (all p<0.05) directly associated with increased PPPM pharmacy costs ($621 low, $1,093 medium, and $1,572 high), but also with the lowest inpatient ($963 low, $960 medium, and $629 high) and outpatient ($1,087 low, $1,068 medium, and $776 high) costs, leading to the highest total costs in the medium adherence group but similar costs in the high and low adherence groups ($2,599 low, $3,163 medium, and $2,869 high). The high adherence group also had the lowest number of inpatient admissions. Significantly increased pharmacy costs associated with the high TPTD adherence group were offset by significantly fewer inpatient admissions, fewer repeated HFx, and lower inpatient and outpatient costs.
    Bone 12/2013; · 4.46 Impact Factor
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    ABSTRACT: The frequency and financial impact of potential drug-drug interactions (DDIs) and drug-condition interactions (DCIs) in patients with painful diabetic peripheral neuropathy (DPN) treated with either pregabalin or duloxetine were compared. This retrospective cohort study was conducted using a large U.S. administrative claims database. Patients selected for study inclusion had a diagnosis of DPN and were newly initiated on either pregabalin or duloxetine between July 1, 2008, and October 1, 2010. Data on potential DDIs and DCIs were collected. Health care costs were measured as the sum of gross covered payments for all medical and prescription claims incurred during the six months after the index date. The study sample comprised 2499 pregabalin users and 1354 duloxetine users. Among pregabalin users, 48 (1.8%) had at least one potential pregabalin DCI; none had potential pregabalin DDIs. Among duloxetine users, 966 (71%) had at least one potential duloxetine DDI or DCI. The frequencies of potential DDIs and DCIs differed significantly between pregabalin and duloxetine users (p < 0.001). Potential duloxetine DDIs and DCIs were associated with a significant increase in mean health care costs in duloxetine users (p = 0.002). Potential pregabalin DDIs and DCIs were not associated with additional health care costs in pregabalin users. Among patients with painful DPN treated with either pregabalin or duloxetine, the frequency of potential duloxetine DDIs and DCIs was substantially higher than that of pregabalin. Potential DDIs and DCIs were associated with significantly increased health care costs in duloxetine users.
    American journal of health-system pharmacy: AJHP: official journal of the American Society of Health-System Pharmacists 12/2013; 70(24):2207-17. · 2.10 Impact Factor
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    ABSTRACT: This study compared the number of, and expenditures on, first-line intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections between patients who were treated with aflibercept or ranibizumab for wet age-related macular degeneration (AMD). This was a retrospective cohort study based on U.S. administrative claims data. Selected patients had initiated first-line intravitreal anti-VEGF treatment with ranibizumab or aflibercept (index date) between November 18, 2011 and April 30, 2013, were aged ≥18 years on the index date, had 12 months of continuous insurance enrollment prior to the index date (baseline period), were diagnosed with wet AMD during the baseline period or on the index date, and had at least 6 or 12 months of follow-up enrollment after the index date without switching to a different anti-VEGF agent (follow-up periods). Outcomes measured within the 6 and 12 month follow-up periods included the number of, and healthcare expenditures on, intravitreal anti-VEGF injections. Multivariable regressions compared the outcomes between aflibercept and ranibizumab. The 6 months analyses included 319 aflibercept patients and 1,054 ranibizumab patients (12 month analyses: 57 and 374, respectively). Over the first 6 months after the index date, neither the number of injections (aflibercept mean = 3.8 ± 1.6; ranibizumab mean = 3.9 ± 1.9) nor the expenditures on injections (aflibercept mean = $7 468 ± $4 211; ranibizumab mean = $7 816 ± $4 834) differed significantly between aflibercept patients and ranibizumab patients (in multivariable regression treating ranibizumab as reference: incidence rate ratio = 0.97, 95% confidence interval [CI] 0.91-1.03, P = 0.277; cost ratio = 0.96, 95% CI 0.89-1.04, P = 0.338). Differences were also insignificant in the 12 month analyses. The overall mean days between injections differed by only 1.8 (95% CI 1.3-2.3) days between the aflibercept patients and ranibizumab patients (42.4 and 40.6, respectively). Aflibercept and ranibizumab were used at a similar frequency resulting in similar intravitreal anti-VEGF injection healthcare expenditures among wet AMD patients initiating first-line intravitreal anti-VEGF treatment.
    Advances in Therapy 12/2013; · 2.44 Impact Factor
  • Stephen S Johnston
    Sexually transmitted diseases 07/2013; 40(7):582-3. · 2.58 Impact Factor
  • S S Johnston, T Kamath, N Shi, R Fowler, B C Chu, W Reiss
    Value in Health 05/2013; 16(3):A225-6. · 2.19 Impact Factor
  • T Juday, S S Johnston, A Farr, B C Chu, T Hebden
    Value in Health 05/2013; 16(3):A85. · 2.19 Impact Factor
  • S S Johnston, T Kamath, N Shi, R Fowler, B C Chu, W Reiss
    Value in Health 05/2013; 16(3):A218. · 2.19 Impact Factor
  • L A Palmer, A Farr, S S Johnston
    Value in Health 05/2013; 16(3):A219-20. · 2.19 Impact Factor
  • B C Chu, S S Johnston, P Juneau, T Juday
    Value in Health 05/2013; 16(3):A47. · 2.19 Impact Factor
  • T Juday, A Farr, S S Johnston, B C Chu, T Hebden
    Value in Health 05/2013; 16(3):A94. · 2.19 Impact Factor
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    ABSTRACT: The objective of this study was to examine the association between teriparatide adherence and healthcare utilization and costs in real-world US kyphoplasty/vertebroplasty (KV) patients. Among KV patients newly initiating teriparatide, significantly increased pharmacy costs associated with high teriparatide adherence were offset by significantly lower inpatient utilization and medical costs. INTRODUCTION: This study seeks to examine the association between teriparatide adherence and healthcare utilization/costs in real-world US KV patients. METHODS: Identified patients from a large US administrative claims database were aged 50+ with KV from 1/1/2002-12/31/2010 (first observed KV = index). Included individuals had 6+ months of pre-index continuous enrollment and no pre-index teriparatide, cancer, or Paget's disease. Follow-up period for patients initiating teriparatide was ≤36 months post-index. Three teriparatide adherence cohorts were constructed using the proportion of days covered (PDC) during the follow-up period: low (PDC ≤ 0.5), medium (PDC >0.5-≤ 0.8), and high (PDC >0.8). Repeated KV admissions, any inpatient admission, number of inpatient admissions, and per-patient-per-month (PPPM) inpatient, outpatient, pharmacy, and total costs were compared between cohorts. The associations between teriparatide adherence and healthcare utilization/costs were examined using multivariable regression models, adjusting for patient demographics and clinical characteristics. RESULTS: Included were 1,568 patients (mean age, 75 years; 82 % female): 403 (26 %) had low adherence, 382 (24 %) medium, and 783 (50 %) high. After multivariable adjustment, high adherence was significantly associated with the lowest PPPM inpatient (low = $1,287; medium = $1,005; high = $678) and outpatient (low = $1,464; medium = $1,244; high = $1,077) medical costs, but with increased pharmacy costs (low = $752; medium = $1,159; high = $1,616; all P < 0.05), leading to similar total costs (low = $3,344; medium = $3,376; high = $3,351) between cohorts; high adherence was also significantly associated with the lowest odds of repeated KV admission, any inpatient admission, and number of inpatient admissions (all P < 0.05). CONCLUSIONS: Among KV patients initiating teriparatide, significantly increased pharmacy costs associated with high teriparatide adherence were offset by significantly lower inpatient utilization and medical costs.
    Osteoporosis International 03/2013; · 4.04 Impact Factor
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    ABSTRACT: OBJECTIVE: This study compared the incidence and hazard of ICD-9-CM-coded infections and severe infections in rheumatoid arthritis (RA) patients treated with subsequent-line (SL) BIOs (BIO) after switching from first-line (FL) anti-TNF therapy (anti-TNF). METHODS: Retrospective analysis of a large U.S. claims database. RA patients initiating an FL anti-TNF between 1/1/2004 and 3/31/2010 were identified and followed forward in time to capture all SL BIO episodes through 3/31/2010. SL BIO episodes were classified into: abatacept, adalimumab, etanercept, infliximab, or rituximab. Multivariate mixed-effects survival models compared the hazard of infections and severe infections across the SL BIO episodes with adjustment for demographic and clinical confounders. RESULTS: In total, 4332 SL BIO episodes were identified: mean age 55 years; 80% female. In adjusted analyses: when compared to rituximab, the hazard of all infections was significantly higher for adalimumab (hazard ratio [HR] = 1.31, 95% confidence interval [CI] = 1.09-1.55), etanercept (HR = 1.44, 95% CI = 1.20-1.72), and infliximab (HR = 1.30, 95% CI = 1.07-1.57), and insignificantly different for abatacept (HR = 1.18, 95% CI = 0.98-1.41); when compared to rituximab, the hazard of severe infection was significantly higher for infliximab (HR = 1.62, 95% CI = 1.03-2.55), and insignificantly different for abatacept (HR = 1.21, 95% CI = 0.78-1.88), adalimumab (HR = 1.10, 95% CI = 0.72-1.68), and etanercept (HR = 1.27, 95% CI = 0.83-1.95). CONCLUSIONS: In RA patients treated with SL BIO, a 30-44% higher hazard of all infection was observed in anti-TNFs versus rituximab with a 62% higher hazard of severe infection observed in infliximab versus rituximab. This study used a non-randomized, observational design and is therefore subject to confounding from unmeasured factors that influence both treatment choice and infection risk.
    Seminars in arthritis and rheumatism 02/2013; · 4.72 Impact Factor
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    ABSTRACT: Timely linkage to appropriate care after human immunodeficiency virus (HIV) diagnosis is critical to optimizing patient outcomes. Medicaid is the largest source of health care coverage for patients with HIV in the United States, yet no studies of linkage to appropriate HIV care have focused solely on the Medicaid population. This is a retrospective study using Medicaid claims data from 15 states. Study sample comprised patients aged 18 to 64 years with 1 or more HIV tests between January 1, 2003, to May 1, 2010, followed or accompanied by HIV diagnosis. The "Test Index" corresponded to the HIV test that was temporally proximate to first HIV diagnosis. Study end point was linkage to appropriate HIV care, defined as receipt of CD4 and viral load tests as per US treatment guidelines. Time-to-event analyses characterized patterns and correlates of linkage to appropriate care. This study included 6684 patients, with a mean age of 35 years, 70% female, and 47% black race. Overall, 21.0% of patients linked to appropriate care within 1 year of the Test Index and 26.4% within 5 years. Compared with whites, blacks had a significantly shorter time to linkage to HIV appropriate care (hazard ratio, 2.034; P < 0.001). These findings in Medicaid patients newly diagnosed with HIV contrast with prior research show disparities in access to HIV care favoring whites. Overall, the proportion of patients who linked to appropriate HIV care was very low given the availability of effective treatment, suggesting a need for more effective interventions promoting timely linkage to appropriate care after diagnosis.
    Sexually transmitted diseases 01/2013; 40(1):18-25. · 2.58 Impact Factor
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    ABSTRACT: This is the first study to compare the incidence and health care costs of medically attended adverse effects in atazanavir- and darunavir-based antiretroviral therapy (ART) among U.S. Medicaid patients receiving routine HIV care. This was a retrospective study using Medicaid administrative health care claims from 15 states. Subjects were HIV patients aged 18 to 64 years initiating atazanavir- or darunavir-based ART from January 1, 2003, to July 1, 2010, with continuous enrollment for 6 months before (baseline) and 6 months after (evaluation period) ART initiation and 1 or more evaluation period medical claim. Outcomes were incidence and health care costs of the following medically attended (International Classification of Diseases, Ninth Revision, Clinical Modification-coded or treated) adverse effects during the evaluation period: gastrointestinal, lipid abnormalities, diabetes/hyperglycemia, rash, and jaundice. All-cause health care costs were also determined. Patients treated with atazanavir and darunavir were propensity score matched (ratio = 3:1) by using demographic and clinical covariates. Multivariable models adjusted for covariates lacking postmatch statistical balance. Propensity-matched study sample included 1848 atazanavir- and 616 darunavir-treated patients (mean age 41 years, 50% women, 69% black). Multivariable-adjusted hazard ratios (HRs) (for darunavir, reference = atazanavir) and per-patient-per-month health care cost differences (darunavir minus atazanavir) were as follows: gastrointestinal, HR = 1.25 (P = 0.04), $43 (P = 0.13); lipid abnormalities, HR = 1.38 (P = 0.07), $3 (P = 0.88); diabetes/hyperglycemia, HR = 0.84 (P = 0.55), $13 (P = 0.69); and rash, HR = 1.11 (P = 0.23), $0 (P = 0.76); all-cause health care costs were $1086 (P<0.001). Too few instances of jaundice (11 in atazanavir and 1 in darunavir) occurred to support multivariable modeling. Medication tolerability can be critical to the success or failure of ART. Compared with darunavir-treated patients, atazanavir-treated patients had significantly fewer instances of medically attended gastrointestinal issues and more instances of jaundice and incurred significantly lower health care costs.
    Value in Health 01/2013; 16(2):418-25. · 2.19 Impact Factor
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    ABSTRACT: Although Internet-based surveys are becoming more common, little is known about agreement between administrative claims data and Internet-based survey self- and proxy-reported health care resource utilization (HCRU) data. This analysis evaluated the level of agreement between self- and proxy-reported HCRU data, as recorded through an Internet-based survey, and administrative claims-based HCRU data. The Child and Household Influenza-Illness and Employee Function study collected self- and proxy-reported HCRU data monthly between November 2007 and May 2008. Data included the occurrence and number of visits to hospitals, emergency departments, urgent care centers, and outpatient offices for a respondent's and his or her household members' care. Administrative claims data from the MarketScan® Databases were assessed during the same time and evaluated relative to survey-based metrics. Only data for individuals with employer-sponsored health care coverage linkable to claims were included. The Kappa (κ) statistic was used to evaluate visit concordance, and the intraclass correlation coefficient was used to describe frequency consistency. Agreement for presence of a health care visit and the number of visits were similar for self- and proxy-reported HCRU data. There was moderate to substantial agreement related to health care visit occurrence between survey-based and claims-based HCRU data for inpatient, emergency department, and office visits (κ: 0.47-0.77). There was less agreement on health care visit frequencies, with intraclass correlation coefficient values ranging from 0.14 to 0.71. This study's agreement values suggest that Internet-based surveys are an effective method to collect self- and proxy-reported HCRU data. These results should increase confidence in the use of the Internet for evaluating disease burden.
    Value in Health 05/2012; 15(3):458-65. · 2.19 Impact Factor
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    ABSTRACT: In treatment of human immunodeficiency virus (HIV), high levels of adherence to combination antiretroviral therapy (cART) are required to prevent failure of virologic suppression, development of drug resistance, and permanent loss of therapeutic options. No published research has assessed the association between cART prescription cost sharing and adherence to cART. To analyze the association between cART prescription cost sharing and adherence to initial cART in commercially insured antiretroviral (ARV)-naïve patients with HIV. This retrospective observational cohort study used 2002-2008 data from a large U.S. claims database of more than 56 million commercially insured individuals. Study subjects were patients aged 18 years or older who initiated cART during the period January 1, 2003, to December 31, 2007, had no ARV claims during the 6-month period prior to the initiation date, and had at least 1 ICD-9-CM diagnosis code for HIV infection (042, 795.71, V08) from 12 months before to 12 months after cART initiation. A minimum 12-month period of continuous enrollment after cART initiation was used to construct a patient-quarter repeated measures panel dataset in which each quarter of data that a patient contributed represented an observation. The evaluation period extended from cART initiation until the occurrence of 1 of the following events: addition of an ARV that was not part of the initial cART regimen, 30-day gap in possession of an ARV within the initiated cART regimen, hospitalization of 30 or more days, loss to follow-up due to study end (December 31, 2008), or disenrollment. The study's outcome was quarterly adherence to cART, defined as the number of days within the quarter that a patient possessed all components of the initial cART regimen. Each patient's cART cost-sharing amount was calculated per 30-day supply of the entire cART regimen. Adherence was dichotomized for analysis at the clinically meaningful thresholds of 95% and 78%. The dichotomized adherence outcomes were separately modeled using population-averaged generalized estimating equations (GEEs) with time-varying and time-constant covariates and an exchangeable working correlation structure. Independent variables included cost-sharing amount; sequential quarter number after cART initiation; interaction between cost-sharing amount and sequential quarter number (to capture any changes in the association of cost sharing with adherence that may occur over time after initiation of cART); and patient demographic, clinical, and insurance characteristics. For each sequential quarter after cART initiation, the GEE models were used to generate average predicted probabilities of adherence reaching each threshold (95% and 78%) at cost-sharing levels of $25, $75, and $144, which represented the 25th, 75th, and 90th percentiles of the cost-sharing distribution, respectively. The study sample included 19,199 patient-quarters and 3,731 patients: mean age 41.1 years; 83.2% male; mean (SD) duration of post-index period 5.1 (4.2) quarters; mean (SD) daily cART pill count 3.2 (2.2); mean (median) cost sharing per 30-day supply of the entire cART regimen $67 ($40). In the unadjusted analyses of patient-quarters, mean adherence ranged from 97.2% for cost-sharing levels within the 0-20th percentiles (from $0 to $20 per 30-day cART supply) to 94.0% for cost-sharing levels exceeding the 80th percentile (from $84 to $3,832 per 30-day cART supply). In the adjusted analyses for the second quarter (25th percentile of follow-up duration, n = 3,117 cases still under observation) at the cost-sharing levels of $25, $75, and $144, the predicted probabilities of at least 95% adherence were 0.782, 0.770, and 0.752, respectively, and the predicted probabilities of at least 78% adherence were 0.936, 0.931, and 0.924, respectively. The differences in the predicted probabilities of adherence grew over time. By the seventh quarter (the 75th percentile of follow-up duration, n = 1,096 cases still under observation), the predicted probabilities were 0.773, 0.746, and 0.707 for 95% adherence and 0.933, 0.922, and 0.904 for 78% adherence at cost-sharing levels of $25, $75, and $144, respectively. Increasing cART prescription cost sharing was associated with modestly decreased probability of maintaining clinically meaningful levels of cART adherence.
    Journal of managed care pharmacy: JMCP 03/2012; 18(2):129-45. · 2.41 Impact Factor

Publication Stats

333 Citations
122.46 Total Impact Points

Institutions

  • 2013–2014
    • Truven Health Analytics
      Ann Arbor, Michigan, United States
  • 2008–2012
    • Thomson Reuters
      New York City, New York, United States
  • 2011
    • University of California, Irvine
      • Department of Medicine
      Irvine, CA, United States
    • Northwestern University
      • Division of Cardiology (Dept. of Medicine)
      Evanston, IL, United States
  • 2010
    • Penn State Hershey Medical Center and Penn State College of Medicine
      Hershey, Pennsylvania, United States
    • MedImmune, LLC
      Maryland, United States