Stephen S Johnston

Truven Health Analytics, Ann Arbor, Michigan, United States

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Publications (59)173.65 Total impact

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    ABSTRACT: Introduction Patients with type 2 diabetes mellitus (T2DM) must remain adherent and persistent on antidiabetic medications to optimize clinical benefits. This analysis compared adherence and persistence among adults initiating dipeptidyl peptidase-4 inhibitors (DPP-4is), sulfonylureas (SUs), and thiazolidinediones (TZDs) and between patients initiating saxagliptin or sitagliptin, two DPP-4is. Methods This retrospective cohort study utilized the US MarketScan® (Truven Health Analytics, Ann Arbor, MI, USA) Commercial and Medicare Supplemental health insurance claims databases. Adults aged ≥18 years with T2DM who initiated a DPP-4i, SU, or TZD from January 1, 2009 to January 31, 2012 were included. Patients must have been continuously enrolled for ≥1 year prior to and ≥1 year following initiation. Adherence was measured using proportion of days covered (PDC), with PDC ≥ 0.80 considered adherent. Persistence was measured as time to discontinuation, defined as last day with drug prior to a 60+ days gap in therapy. Multivariable logistic regression and Cox proportional hazards models compared the outcomes between cohorts, controlling for baseline differences. Results The sample included 238,372 patients (61,399 DPP-4i, 134,961 SU, 42,012 TZD). During 1-year follow-up, 47.3% of DPP-4i initiators, 41.2% of SU initiators, and 36.7% of TZD initiators were adherent. Adjusted odds of adherence were significantly greater among DPP-4i initiators than SU (adjusted odds ratio [AOR] = 1.678, P P P P P P Conclusions US adults with T2DM who initiated DPP-4i therapy, particularly saxagliptin, had significantly better adherence and persistence compared with patients who initiated SUs or TZDs.
    Advances in Therapy 12/2014; · 2.44 Impact Factor
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    ABSTRACT: Greater adherence to medications has been broadly demonstrated to be associated with improved clinical outcomes. However, there is limited real-world evidence on adherence to glucagon-like peptide-1 receptor agonist (GLP-1RA) therapy in patients with type 2 diabetes mellitus (T2DM). This retrospective cohort study used United States administrative claims data to compare adherence to GLP-1RAs in T2DM patients initiating exenatide once weekly (QW), exenatide twice daily (BID), or once-daily liraglutide (initiated therapy = index therapy). Patients were included if they had T2DM, were GLP-1RA-naïve, initiated a GLP-1RA from 02/01/2012-01/31/2013 (date of initiation = index), were ≥18 years at index, and had continuous enrollment for 12 months before (baseline) to 6 months after index (follow-up). Study outcome was index GLP-1RA adherence (proportion of days covered [PDC] during follow-up, dichotomized at ≥80% vs. <80%, and at ≥90% vs. <90%). Multivariable logistic regressions compared adherence between the GLP-1RAs, adjusting for potential confounders. Sensitivity analyses were performed separating liraglutide by dose (1.2 mg/1.8 mg). Study sample included 4,041 exenatide QW, 4,586 exenatide BID, and 14,211 liraglutide (6,641 1.2 mg, 7,570 1.8 mg) patients. Median unadjusted PDC values were 0.783 for exenatide QW, 0.500 exenatide BID, 0.722 liraglutide, 0.761 liraglutide 1.2 mg, and 0.683 liraglutide 1.8 mg. Compared with patients treated with either exenatide BID or liraglutide, patients treated with exenatide QW had a statistically significantly greater multivariable-adjusted odds of achieving adherence of ≥80% (odds ratio vs. exenatide QW (OR) = 0.41 for exenatide BID; 0.80, liraglutide; 0.87, liraglutide 1.2 mg; 0.75, liraglutide 1.8 mg) and ≥90% (OR = 0.31 for exenatide BID; 0.60 liraglutide; 0.66 liraglutide 1.2 mg; 0.56 liraglutide 1.8 mg) (all P < 0.001). Patients initiating exenatide QW had significantly higher adjusted odds of adherence compared with patients initiating other GLP-1RAs. Given differences in adherence across the GLP-1RAs, research correlating these factors with clinical and economic outcomes is warranted.
    Advances in Therapy 11/2014; · 2.44 Impact Factor
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    ABSTRACT: There is a lack of data comparing the protease inhibitors (PIs) atazanavir (ATV) and darunavir (DRV) in a real-world setting. This study compared persistence (time to switch/discontinuation) to therapy between ATV-treated and DRV-treated patients with human immunodeficiency virus (HIV).
    Journal of the International AIDS Society 11/2014; 17(4 Suppl 3):19538. · 4.21 Impact Factor
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    ABSTRACT: Background: The aim of this study was to compare the incidence rate of suicidality and suicide attempt among patients initiating efavirenz (EFV)-containing versus EFV-free antiretroviral (ARV) regimens, adjusting for confounding factors. Methods: This was a cohort analysis using administrative claims data from a US commercial and a public insurance database (Medicaid) spanning 2006-2013. We identified ARV-naive patients age ≥12 years initiating an EFV-containing or EFV-free regimen with ≥6 months of continuous enrollment prior to ARV initiation. Suicidality was defined as ICD-9-CM diagnosis (Dx) codes for suicidal ideation or attempt. Suicide attempt was defined as 1) an inpatient or emergency department claim with a Dx code for suicide attempt and 2) an expanded definition that also included Dx codes for injuries consistent with suicide attempt + a psychiatric Dx during the same encounter. The outcomes were identified from ARV initiation until the earliest of the end of exposure, enrollment or the study period. Outcomes were compared using hazard ratios (HRs) from a propensity score (PS) adjusted Cox model accounting for baseline demographics, comorbidities and comedications. Results: There were 19,983 patients (EFV: 11,187, EFV-free: 8,796) in the commercial database; 83% male and mean age 40. In the Medicaid database, there were 5,154 patients (EFV: 2,224, EFV-free: 2,930); 53% male and mean age 41. In both databases, patients initiating an EFV-free regimen had a higher prevalence of depression and other psychiatric conditions. Incidence rates for all outcomes were higher in the Medicaid population. In adjusted analyses, EFV use was not associated with suicidality or the expanded definition of suicide attempt (figures). For the restrictive definition, the point estimate was in the opposite direction in the commercial vs. the Medicaid database, which may be reflective of the patient populations and the small number of events. Conclusion: In this analysis of two large real world databases, HIV patients with depression and psychiatric conditions were less likely to be prescribed EFV. Despite PS-adjustment, we did not find conclusive evidence of an increased risk of suicidality or suicide attempt among patients initiating an EFV-containing regimen.
    IDWeek 2014 Meeting of the Infectious Diseases Society of America; 10/2014
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    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: Background: Atypical antipsychotics (AA) differ from one another in their adverse event (AE) profiles. Patient-specific pre-existing risk factors for AEs, including comorbidities and concomitant medications, may render the use of certain AAs potentially inappropriate, and others relatively safer or more tolerable. Objective: To quantify the prevalence of pre-existing risk factors for AEs and potential drug-drug interactions (DDIs) associated with AA treatment among patients with schizophrenia (SCZ), bipolar disorder (BD), or major depressive disorder (MDD) newly-initiating AA treatment. Methods: Retrospective, observational study using US claims databases. Patients identified had newly-initiated on a single AA (1/1/2010-11/30/2011; index date), were aged 18-64 years, had insurance enrolment for 12 months pre- (baseline) and 1 month post-index, and had ≥1 medical claim with an ICD-9-CM diagnosis of SCZ, BD, or MDD during baseline. A comprehensive list of AE risk factors, including potential DDIs, was developed based on AA package inserts. Administrative claims-based identification algorithms flagged the presence of each medical risk factor during baseline and identified concomitant prescribing of medications (90 days pre- to 30 days post-index) potentially causing DDIs with AAs. Results: Of 97,010 patients identified, mean age was 41.2 years and 66.7% were female. Among patients initiating AA treatment, prevalence of pre-existing AE risk factors were aripiprazole 32.2%; olanzapine 51.6%; ziprasidone 75.6%; quetiapine 77.4%; risperidone 82.5%. Conclusions: Despite the availability of several AAs to treat psychiatric conditions, pre-existing AE risk factors can limit patient treatment options. Given inter-AA variability in risk factors, open access to AA may help to optimize appropriate prescribing.
    Current Drug Safety 06/2014;
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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
  • Annals of the Rheumatic Diseases 01/2014; 72(Suppl 3):A774-A774. · 9.27 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; · 2.24 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; · 2.24 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. · 2.89 Impact Factor
  • T Juday, S S Johnston, A Farr, B C Chu, T Hebden
    Value in Health 05/2013; 16(3):A85. · 2.89 Impact Factor
  • S S Johnston, T Kamath, N Shi, R Fowler, B C Chu, W Reiss
    Value in Health 05/2013; 16(3):A218. · 2.89 Impact Factor
  • L A Palmer, A Farr, S S Johnston
    Value in Health 05/2013; 16(3):A219-20. · 2.89 Impact Factor
  • B C Chu, S S Johnston, P Juneau, T Juday
    Value in Health 05/2013; 16(3):A47. · 2.89 Impact Factor
  • T Juday, A Farr, S S Johnston, B C Chu, T Hebden
    Value in Health 05/2013; 16(3):A94. · 2.89 Impact Factor

Publication Stats

368 Citations
173.65 Total Impact Points


  • 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