Walid F Gellad

U.S. Department of Veterans Affairs, Washington, D. C., DC, United States

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Publications (44)321.23 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Self-monitoring of blood glucose is a costly component of care for diabetes mellitus, with unclear benefits for patients not taking insulin. Veterans with dual Department of Veterans Affairs (VA) and Medicare benefits have access to test strips through both systems, raising the potential for overuse.
    JAMA Internal Medicine 11/2014; · 13.25 Impact Factor
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    ABSTRACT: Nursing home patients with dementia may be more likely to suffer adverse drug events from suboptimal prescribing. Previous studies have not used national samples, nor have they examined multiple types of suboptimal prescribing by dementia severity.
    The Annals of pharmacotherapy. 11/2014;
  • JAMA Pediatrics 09/2014; · 4.28 Impact Factor
  • JAMA The Journal of the American Medical Association 08/2014; 312(5):558-9. · 29.98 Impact Factor
  • Yan Tang, Walid F Gellad, Aiju Men, Julie M Donohue
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    ABSTRACT: Little is known about how Medicare Part D plan features influence choice of generic versus brand drugs. To examine the association between Part D plan features and generic medication use. Data from a 2009 random sample of 1.6 million fee-for-service, Part D enrollees aged 65 years and above, who were not dually eligible or receiving low-income subsidies, were used to examine the association between plan features (generic cost-sharing, difference in brand and generic copay, prior authorization, step therapy) and choice of generic antidepressants, antidiabetics, and statins. Logistic regression models accounting for plan-level clustering were adjusted for sociodemographic and health status. Generic cost-sharing ranged from $0 to $9 for antidepressants and statins, and from $0 to $8 for antidiabetics (across 5th-95th percentiles). Brand-generic cost-sharing differences were smallest for statins (5th-95th percentiles: $16-$37) and largest for antidepressants ($16-$64) across plans. Beneficiaries with higher generic cost-sharing had lower generic use [adjusted odds ratio (OR)=0.97, 95% confidence interval (CI), 0.95-0.98 for antidepressants; OR=0.97, 95% CI, 0.96-0.98 for antidiabetics; OR=0.94, 95% CI, 0.92-0.95 for statins]. Larger brand-generic cost-sharing differences and prior authorization were significantly associated with greater generic use in all categories. Plans could increase generic use by 5-12 percentage points by reducing generic cost-sharing from the 75th ($7) to 25th percentiles ($4-$5), increasing brand-generic cost-sharing differences from the 25th ($25-$26) to 75th ($32-$33) percentiles, and using prior authorization and step therapy. Cost-sharing features and utilization management tools were significantly associated with generic use in 3 commonly used medication categories.
    Medical care 06/2014; 52(6):541-8. · 3.24 Impact Factor
  • JAMA The Journal of the American Medical Association 04/2014; 311(13):1353-5. · 29.98 Impact Factor
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    ABSTRACT: To assess the association between multiple pharmacy use and medication adherence and potential drug-drug interactions (DDIs) in older adults. Cross-sectional propensity score-weighted analysis. 2009 claims data. A nationally representative sample of 926,956 Medicare Part D beneficiaries aged 65 and older continuously enrolled in fee-for-service Medicare and Part D that year who filled one or more prescriptions at a community retail or mail order pharmacy. Multiple pharmacy use was defined as concurrent (overlapping time periods) or sequential use (non-overlapping time periods) of ≥2 pharmacies in the year. Medication adherence was calculated using a proportion of days covered of 0.80 or greater for eight therapeutic categories (beta-blockers, renin angiotensin system antagonists, calcium channel blockers, statins, sulfonylureas, biguanides (metformin), thiazolidinediones, and dipeptidyl peptidase-IV inhibitors). Potential DDIs arising from use of certain drugs across a broad set of classes were defined as the concurrent filling of two interacting drugs. Overall, 38.1% of the sample used multiple pharmacies. Those using multiple pharmacies (concurrently or sequentially) consistently had higher adjusted odds of nonadherence (ranging from 1.10 to 1.31, P < .001) across all chronic medication classes assessed after controlling for sociodemographic, health status, and access to care factors than single pharmacy users. The adjusted predicted probability of exposure to a DDI was also slightly higher for those using multiple pharmacies concurrently (3.6%) than for single pharmacy users (3.2%, adjusted odds ratio (AOR) = 1.11, 95% confidence interval (CI) = 1.08-1.15) but lower in individuals using multiple pharmacies sequentially (2.8%, AOR = 0.85, 95% CI = 0.81-0.91). Filling prescriptions at multiple pharmacies was associated with lower medication adherence across multiple chronic medications and a small but statistically significant greater likelihood of DDIs in concurrent pharmacy users.
    Journal of the American Geriatrics Society 02/2014; 62(2):244-52. · 4.22 Impact Factor
  • New England Journal of Medicine 01/2014; 370(1):81. · 54.42 Impact Factor
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    ABSTRACT: Objectives: A "chiral switch" occurs in the pharmaceutical market when a drug made up of 2 enantiomer forms is replaced with a purified single-enantiomer version, often in the context of a patent expiration. We studied the prevalence of chiral switching in the United States over the past decade, including trends in use of, and expenditures on, these products in Medicaid. Study Design: Retrospective analysis. Methods: We used US Adopted Names prefixes (lev/levo/ar/es/dex/dextro) to identify all single-enantiomer drugs approved from 2001 to 2011. From publicly available US Food and Drug Administration (FDA) approval documents, we extracted the characteristics of the pivotal premarket trials for the single enantiomers. Specifically, we evaluated whether the single enantiomer was directly compared with the precursor racemic drug and whether there was evidence of superior efficacy. We used quarterly drug expenditure data from each state Medicaid program to chart trends in use of, and spending on, the single-enantiomer products and their racemic precursors during the study period. Results: From 2001 to 2011, the FDA approved 9 single-enantiomer products: dexlansoprazole, levoleucovorin, levocetirizine, armodafinil, arformoterol, eszopiclone, escitalopram, dexmethylphenidate, and esomeprazole. Of those 9 drugs, 3 had at least 1 pre-approval randomized trial that included the racemic precursor as a direct comparator, but there was no evidence of superiority of the single enantiomer over the racemic at comparable doses. Between 2001 and 2011, US Medicaid programs spent approximately $6.3 billion on these 9 single-enantiomer drugs. Conclusions: Recently approved single-enantiomer drugs showed no evidence of superior efficacy over the older racemic precursors in the pivotal trials leading to their approval, and in a majority of cases, they were not directly compared.
    The American journal of managed care 01/2014; 20(3):e90-7. · 2.12 Impact Factor
  • 60th Meeting of American Academy of Child and Adolescent Psychiatry; 10/2013
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    ABSTRACT: BACKGROUND: Medicare Part D and the U.S. Department of Veterans Affairs (VA) use different approaches to manage prescription drug benefits, with implications for spending. Medicare relies on private plans with distinct formularies, whereas the VA administers its own benefit using a national formulary. OBJECTIVE: To compare overall and regional rates of brand-name drug use among older adults with diabetes in Medicare and the VA. DESIGN: Retrospective cohort. SETTING: Medicare and the VA, 2008. PATIENTS: 1 061 095 Medicare Part D beneficiaries and 510 485 veterans aged 65 years or older with diabetes. MEASUREMENTS: Percentage of patients taking oral hypoglycemics, statins, and angiotensin-converting enzyme (ACE) inhibitors or angiotensin-receptor blockers (ARBs) who filled brand-name drug prescriptions and percentage of patients taking long-acting insulins who filled analogue prescriptions. Sociodemographic- and health status-adjusted hospital referral region (HRR) brand-name drug use was compared, and changes in spending were calculated if brand-name drug use in 1 system mirrored the other. RESULTS: Brand-name drug use in Medicare was 2 to 3 times that in the VA: 35.3% versus 12.7% for oral hypoglycemics, 50.7% versus 18.2% for statins, 42.5% versus 20.8% for ACE inhibitors or ARBs, and 75.1% versus 27.0% for insulin analogues. Adjusted HRR-level brand-name statin use ranged (from the 5th to 95th percentiles) from 41.0% to 58.3% in Medicare and 6.2% to 38.2% in the VA. For each drug group, the 95th-percentile HRR in the VA had lower brand-name drug use than the 5th-percentile HRR in Medicare. Medicare spending in this population would have been $1.4 billion less if brand-name drug use matched that of the VA. LIMITATION: This analysis cannot fully describe the factors underlying differences in brand-name drug use. CONCLUSION: Medicare beneficiaries with diabetes use 2 to 3 times more brand-name drugs than a comparable group within the VA, at substantial excess cost. PRIMARY FUNDING SOURCE: U.S. Department of Veterans Affairs, National Institutes of Health, and Robert Wood Johnson Foundation.
    Annals of internal medicine 06/2013; · 13.98 Impact Factor
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    ABSTRACT: PURPOSE: The results of a survey assessing Medicare Part D enrollment, the use of pharmacotherapies for chronic diseases, and other medication-use issues in a population of elderly military veterans are presented. METHODS: Medicare-eligible (i.e., ≥65 years of age) patients with documented recent service use at a single Veterans Affairs (VA) medical center were targeted for a mail survey. Women were oversampled (20%) to ensure an adequate sample size; the sample was weighted to adjust for this oversampling. Usable survey data were received from 458 survey respondents. RESULTS: Nearly all respondents (93.2%) reported having one or more chronic conditions; of those, 93.3% reported regular use of multiple drug therapies, and 30.1% reported using medications prescribed by both VA and non-VA providers for the same chronic condition. About half of the survey respondents reported at least one office visit with a non-VA physician during the previous year, and 55.8% reported obtaining medications from non-VA pharmacies. More than half (54.1%) of the respondents reported non-VA medication coverage, with 21.2% indicating they were enrolled in Medicare Part D. Among the respondents who reported obtaining medications from non-VA pharmacies, substantial proportions reported discussing those medications with VA physicians never (38.4%) or infrequently (15.7%). CONCLUSION: Although large proportions of Medicare-eligible veterans take multiple medications and use non-VA health care services and pharmacies, many do not discuss medications obtained outside the VA system with VA physicians, suggesting that increased efforts to enhance provider-patient communication and medication reconciliation across VA and non-VA systems of care may be warranted.
    American journal of health-system pharmacy: AJHP: official journal of the American Society of Health-System Pharmacists 05/2013; 70(9):804-813. · 2.10 Impact Factor
  • Y Tang, W F Gellad, A Men, J M Donohue
    Value in Health 05/2013; 16(3):A248. · 2.19 Impact Factor
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    ABSTRACT: BACKGROUND AND OBJECTIVE: Little is known about contraceptive use and adherence in the Veterans Health Administration (VA) health care system. We assessed contraceptive adherence among women who were using hormonal contraception (pill, patch, ring, and injectable) and examined the relationships between race/ethnicity and months of contraceptive supply dispensed with contraceptive adherence. MATERIALS AND METHODS: We conducted a retrospective analysis of data from national VA administrative databases. The study cohort included all women veterans ages 18-45 years who made at least 1 visit to a VA primary care clinic or women's health clinic during the study period (FY 2008: Oct. 1, 2007, through Sept. 30, 2008) and who had hormonal contraceptive (pills, patch, vaginal ring, or injection) coverage during the first week of the study timeframe. Women who had undergone hysterectomy or tubal sterilization or who used an IUD or implant in FY 2008 were excluded. We constructed several patient-level indicators of contraceptive adherence over FY 2008. These indicators included gaps of ≥7 days between refills, total months of contraceptive coverage, and presence of contraceptive coverage during the last week of FY 2008. For the last outcome we distinguished between coverage with gaps and continuous coverage throughout the year (perfect adherence). Our primary predictors of interest were race/ethnicity and months of contraceptive supply dispensed. In this analysis, "3-month supply" indicates that the woman received a 3-month supply of contraception at each fill all year; "1-month supply" indicates that the woman received only a 1-month supply at each fill. Anyone who received a 2-month supply or varied months of supply over the course of the year received "other supply." We summarized the indicators of contraceptive adherence (gaps of ≥7 days, total months of contraceptive supply, and contraceptive coverage during the last week of FY 2008) and compared the differences across the key independent variables: race/ethnicity and months of supply dispensed with the use of descriptive statistics and adjusted Cox and logistic regression models. RESULTS: Our study cohort included 6946 women, of whom 46.9% were white, 5.7% Hispanic, 22.2% black, and 3.1% of other race; race information was missing for 22.1%. Most women (83.5%) received a 3-month supply at each fill; 3.6% received a 1-month supply; and 12.9% received other supply. Overall, 64.2% of women had at least 1 gap during the year. Compared to white women, Hispanics were significantly more likely to have a gap (63.7% vs 69.6%, P=.02). Women who received a 1-month supply were significantly more likely than women who received a 3-month supply to have any gap (71.5% vs 63.2%, P=.008). Women had a mean of 9.2 months of contraceptive coverage over the year, with Hispanics and blacks having fewer months of coverage than whites (8.9 and 9.0 months vs 9.3 months, respectively, P<.001). Women who received a 1-month contraceptive supply had significantly fewer months of coverage than those who received a 3-month supply (6.9 vs 9.3 months, P<.001). Of the full cohort, 65.6% had contraceptive coverage the last week of the fiscal year, but the majority (66.9%) of these women had experienced one or more gaps during that time. Only 21.7% of women received a full 12 months of contraception with no gaps between refills (perfect adherence). Bivariable analysis found no racial/ethnic differences related to the likelihood of having contraceptives on hand during the last week of FY 2008. Compared to women who received 3-month supplies, those who received only 1-month supplies were significantly less likely to be on a method the last week of the fiscal year (65.5% vs 43.0%, P<.001) and to have achieved perfect adherence than those who received 3-month supplies (22.2% vs 10.8%, P<.001). Kaplan-Meier curves demonstrating time to first gap of ≥7 days between refills showed that Hispanics experienced shorter time to first gap compared to white and black women (P=.02) (Figure). Women who received 1-month supplies experienced shorter time to first gap than those who received 3-month supplies (P<.001). In adjusted Cox regression analysis, Hispanics remained significantly more likely to experience a gap than white women (hazard ratio [HR],1.18; 95% CI,1.03-1.34). Women who received 1-month supplies remained more likely to experience a gap than women who received 3-month supplies (HR, 1.62; 95% CI, 1.39-1.90). Adjusted models of perfect adherence identified no statistically significant differences by race/ethnicity. Women receiving 1-month supplies were significantly less likely to achieve perfect adherence than those receiving 3-month supplies (odds ratio [OR], 0.46; 95% CI, 0.30-0.69).
    American journal of obstetrics and gynecology 03/2013; · 3.28 Impact Factor
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    ABSTRACT: BACKGROUND:: Antipsychotic medications are commonly prescribed to nursing home residents despite their well-established adverse event profiles. Because little is known about their use in Veterans Affairs (VA) nursing homes [ie, Community Living Centers (CLCs)], we assessed the prevalence and risk factors for antipsychotic use in older residents of VA CLCs. METHODS:: This cross-sectional study included 3692 Veterans age 65 or older who were admitted between January 2004 and June 2005 to one of 133 VA CLCs and had a stay of ≥90 days. We used VA Pharmacy Benefits Management data to examine antipsychotic use and VA Medical SAS datasets and the Minimum Data Set to identify evidence-based indications for antipsychotic use (eg, schizophrenia, dementia with psychosis). We used multivariable logistic regression and generalized estimating equations to identify factors independently associated with antipsychotic receipt. RESULTS:: Overall, 948/3692(25.7%) residents received an antipsychotic, of which 59.3% had an evidence-based indication for use. Residents with aggressive behavior [odds ratio (OR)=2.74, 95% confidence interval (CI), 2.04-3.67] and polypharmacy (9+ drugs; OR=1.84, 95% CI, 1.41-2.40) were more likely to receive antipsychotics, as were users of antidepressants (OR=1.37, 95% CI, 1.14-1.66), anxiolytic/hypnotics (OR=2.30, 95% CI, 1.64-3.23), or drugs for dementia (OR=1.52, 95% CI, 1.21-1.92). Those residing in Alzheimer/dementia special care units were also more likely to receive an antipsychotic (OR=1.66, 95% CI, 1.26-2.21). Veterans with dementia but no documented psychosis were as likely as those with an evidence-based indication to receive an antipsychotic (OR=1.10, 95% CI, 0.82-1.47). CONCLUSIONS:: Antipsychotic use is common among VA nursing home residents aged 65 and older, including those without a documented evidence-based indication for use. Further quality improvement efforts are needed to reduce potentially inappropriate antipsychotic prescribing.
    Medical care 11/2012; 50(11):954-960. · 3.24 Impact Factor
  • Archives of internal medicine 10/2012; · 11.46 Impact Factor
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    ABSTRACT: In complex survey sampling, a fraction of a finite population is sampled. Often, the survey is conducted so that each subject in the population has a different probability of being selected into the sample. Further, many complex surveys involve stratification and clustering. For generalizability of the sample to the finite population, these features of the design are usually incorporated in the analysis. While the Wilcoxon rank sum test is commonly used to compare an ordinal variable in bivariate analyses, no simple extension of the Wilcoxon rank sum test has been proposed for complex survey data. With multinomial sampling of independent subjects, the Wilcoxon rank-sum test statistic equals the score test statistic for the group effect from a proportional odds cumulative logistic regression model for an ordinal outcome. Using this regression framework, for complex survey data, we formulate a similar proportional odds cumulative logistic regression model for the ordinal variable, and use an estimating equations score statistic for no group effect as an extension of the Wilcoxon test. The proposed method is applied to a complex survey designed to produce national estimates of the health care use, expenditures, sources of payment, and insurance coverage.
    Applied Statistics 08/2012; 61(4):653-664. · 1.25 Impact Factor
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    ABSTRACT: To describe facility-level variation in two measures of potentially inappropriate prescribing prevalent in Veterans Affairs (VA) facilities-exposure to high-risk medications in elderly adults (HRME) and drug-disease interactions (Rx-DIS)-and to identify facility characteristics associated with high-quality prescribing. Cross-sectional. VA Healthcare System. Veterans aged 65 and older with at least one inpatient or outpatient visit in 2005-2006 (N = 2,023,477; HRME exposure) and a subsample with a history of falls or hip fractures, dementia, or chronic renal failure (n = 305,059; Rx-DIS exposure). Incident use of any HRME (iHRME) and incident Rx-DIS (iRx-DIS) and facility-level rates and facility-level predictors of iHRME and iRx-DIS exposure, adjusting for differences in patient characteristics. Overall, 94,692 (4.7%) veterans had iHRME exposure. At the facility level, iHRME exposure ranged from 1.6% at the lowest facility to 12.8% at the highest (median 4.7%). In the subsample, 9,803 (3.2%) veterans had iRx-DIS exposure, with a facility-level range from 1.3% to 5.8% (median 3.2%). In adjusted analyses, veterans seen in facilities with formal geriatric education had lower odds of iHRME (odds ratio (OR) = 0.86, 95% confidence interval (CI) = 0.77-0.96) and iRx-DIS (OR = 0.95, 95% CI = 0.88-1.01). Patients seen in facilities caring for fewer older veterans had greater odds of iHRME (OR = 1.54, 95% CI = 1.35-1.75) and iRx-DIS exposure (OR = 1.22, 95% CI = 1.11-1.33). Substantial variation in the quality of prescribing for older adults exists across VA facilities, even after adjusting for patient characteristics. Higher-quality prescribing is found in facilities caring for a larger number of older veterans and facilities with formal geriatric education.
    Journal of the American Geriatrics Society 06/2012; 60(7):1222-9. · 4.22 Impact Factor
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    ABSTRACT: The risk of potentially inappropriate medication (PIM), both prescription and over-the-counter, use in dementia patients is high. Informal caregivers often facilitate patients' use of medications, but the effect of caregiver factors on PIM use has not been a focus of previous research. The aim of this study was to examine PIM use in dementia patients and caregivers and identify caregiver risk factors for PIM use in dementia patients. We conducted a secondary data analysis of the baseline wave of the Resources for Enhancing Alzheimer's Caregiver's Health study. The sample comprised 566 persons with dementia aged 65 and older and their coresiding family caregiver. PIM was defined using the 2003 Beers criteria and was examined in both dementia patients and their caregivers. Caregiver and patient risk factors included a range of sociodemographic and health variables. In dementia patients, 33% were taking at least 1 PIM, and 39% of their caregivers were also taking a PIM. In fully adjusted models, the following caregiver factors were associated with an increased risk of dementia patient PIM use: caregiver's own PIM use, spouse caregivers, Hispanic caregivers, and greater number of years that the caregiver has lived in the United States. Increased caregiver age was associated with a decreased risk of PIM use in patients. PIM use may be higher in dementia patients and their informal caregivers compared with the general older adult population. Further, patterns of medication use in 1 member of the dyad may influence PIM risk in the other dyad member. These results suggest that interventions to increase appropriate medication use in dementia patients and their caregivers should target both members of the dyad and target over-the-counter agents along with prescription medications.
    The American journal of geriatric pharmacotherapy. 06/2012; 10(4):230-41.
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    Zachary A Marcum, Walid F Gellad
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    ABSTRACT: Despite the fact that medication adherence has been extensively described in the literature over the last several decades, a quote by Becker and Maiman from over 35 years ago best captures the current state of our understanding: “Patient compliance[sic adherence] has become the best documented, but least understood, health behavior.” Future research is greatly needed to identify and translate safe and effective interventions into routine clinical practice to improve adherence. Only then can we begin to make significant improvements to the medication use process and, in turn, the health of older adults.
    Clinics in Geriatric Medicine 05/2012; 28(2):287-300. · 3.14 Impact Factor

Publication Stats

257 Citations
321.23 Total Impact Points


  • 2010–2012
    • U.S. Department of Veterans Affairs
      • Center for Health Equity Research and Promotion (CHERP)
      Washington, D. C., DC, United States
  • 2011
    • Claremont Graduate University
      • School of Community and Global Health
      Claremont, CA, United States
    • RAND Corporation
      Santa Monica, California, United States
  • 2008–2011
    • University of Pittsburgh
      • • Department of Health Policy & Management
      • • School of Medicine
      • • Division of General Internal Medicine
      Pittsburgh, PA, United States
  • 2006–2008
    • Brigham and Women's Hospital
      • • Division of General Internal Medicine and Primary Care
      • • Department of Medicine
      Boston, MA, United States
  • 2007
    • Harvard Medical School
      • Department of Medicine
      Boston, Massachusetts, United States