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Instrumental variable applications using nursing home prescribing preferences in comparative effectiveness research.

ABSTRACT: Nursing home residents are of particular interest for comparative effectiveness research given their susceptibility to adverse treatment effects and systematic exclusion from trials. However, the risk of residual confounding because of unmeasured markers of declining health using conventional analytic methods is high. We evaluated the validity of instrumental variable (IV) methods based on nursing home prescribing preference to mitigate such confounding, using psychotropic medications to manage behavioral problems in dementia as a case study.A cohort using linked data from Medicaid, Medicare, Minimum Data Set, and Online Survey, Certification and Reporting for 2001-2004 was established. Dual-eligible patients ?65?years who initiated psychotropic medication use after admission were selected. Nursing home prescribing preference was characterized using mixed-effects logistic regression models. The plausibility of IV assumptions was explored, and the association between psychotropic medication class and 180-day mortality was estimated.High-prescribing and low-prescribing nursing homes differed by a factor of 2. Each preference-based IV measure described a substantial proportion of variation in psychotropic medication choice (?(IV???treatment): 0.22-0.36). Measured patient characteristics were well balanced across patient groups based on instrument status (52% average reduction in Mahalanobis distance). There was no evidence that instrument status was associated with markers of nursing home quality of care.Findings indicate that IV analyses using nursing home prescribing preference may be a useful approach in comparative effectiveness studies, and should extend naturally to analyses including untreated comparison groups, which are of great scientific interest but subject to even stronger confounding.

SUBMITTER: Huybrechts KF

PROVIDER: S-EPMC4116440 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature

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Instrumental variable applications using nursing home prescribing preferences in comparative effectiveness research.

Huybrechts Krista F KF Gerhard Tobias T Franklin Jessica M JM Levin Raisa R Crystal Stephen S Schneeweiss Sebastian S

Pharmacoepidemiology and drug safety 20140324 8

<h4>Purpose</h4>Nursing home residents are of particular interest for comparative effectiveness research given their susceptibility to adverse treatment effects and systematic exclusion from trials. However, the risk of residual confounding because of unmeasured markers of declining health using conventional analytic methods is high. We evaluated the validity of instrumental variable (IV) methods based on nursing home prescribing preference to mitigate such confounding, using psychotropic medica ...[more]

PMID: 24664805

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Project description:BACKGROUND:It is unknown whether nitrofurantoin 50 mg normal-release every 6 h (NF50) and nitrofurantoin 100 mg extended-release every 12 h (NF100) are equally effective for treating cystitis in primary care. In the Netherlands, GP prescription of either option largely depends on pharmacy procurement, rather than on patient-related factors. METHODS:GP data between January 2013 and July 2018 were retrospectively collected. Inclusion criteria were the use of nitrofurantoin for uncomplicated cystitis, complicated cystitis or cystitis in pregnancy. Criteria for early and late failure were a second antibiotic prescription for cystitis or pyelonephritis within 14 and 28 days post-prescription, respectively. Crude and confounder-adjusted (CA) risk differences (RDs) were estimated using linear regression. Instrumental variable analysis and CA instrumental variable analysis used GP practice proportion of NF50 versus NF100 use as the instrumental variable. RESULTS:For uncomplicated cystitis (n=46855), treatment with NF50 and NF100 resulted in late failure in 9.7% and 9.6%, respectively. The CA RD, instrumental variable RD and CA instrumental variable RD were 0.2% (95% CI=-0.5 to 0.8), -0.7% (95% CI=-1.7 to 0.3) and 0.0% (95% CI=-0.9 to 1.0), respectively. In complicated cystitis (n=10767), late failure occurred in 10.9% and 11.1% after using NF50 and NF100, respectively [CA RD=0.5% (95% CI=-1.2 to 1.8), instrumental variable RD=-0.8% (95% CI=-3.4 to 1.8) and CA instrumental variable RD=-0.3% (95% CI=-3.0 to 2.4)]. For cystitis in pregnancy (n=1087), NF50 and NF100 resulted in late failure in 13.4% and 7.8%, respectively [CA RD=-5.4% (95% CI=-10.0 to -1.4), instrumental variable RD=-8.9% (95% CI=-16.0 to -1.8) and CA instrumental variable RD=-8.9% (95% CI=-16.0 to -1.7)]. No differences were observed in early failure. CONCLUSIONS:In patients with cystitis in pregnancy, NF100 was associated with a lower incidence of late clinical failure compared with NF50. We found no differences in clinical failure between NF50 and NF100 for uncomplicated and complicated cystitis.

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Project description:OBJECTIVES:To compare the risk of major medical events in nursing home residents newly initiated on conventional or atypical antipsychotic medications (APMs). DESIGN:Cohort study, using linked Medicaid, Medicare, Minimum Data Set, and Online Survey Certification and Reporting data. Propensity score-adjusted proportional hazards models were used to compare risks for medical events at a class and individual drug level. SETTING:Nursing homes in 45 U.S. states. PARTICIPANTS:Eighty-three thousand nine hundred fifty-nine Medicaid-eligible residents aged 65 and older who initiated APM treatment after nursing home admission in 2001 to 2005. MEASUREMENTS:Hospitalization for myocardial infarction, cerebrovascular events, serious bacterial infections, and hip fracture within 180 days of treatment initiation. RESULTS:Risks of bacterial infections (hazard ratio (HR) = 1.25, 95% confidence interval (CI) = 1.05-1.49) and possibly myocardial infarction (HR = 1.23, 95% CI = 0.81-1.86) and hip fracture (HR = 1.29, 95% CI = 0.95-1.76) were higher, and risks of cerebrovascular events (HR = 0.82, 95% CI = 0.65-1.02) were lower in participants initiating conventional APMs than in those initiating atypical APMs. Little variation existed between individual atypical APMs, except for a somewhat lower risk of cerebrovascular events with olanzapine (HR = 0.91, 95% CI = 0.81-1.02) and quetiapine (HR = 0.89, 95% CI = 0.79-1.02) and a lower risk of bacterial infections (HR = 0.83, 95% CI = 0.73-0.94) and possibly a higher risk of hip fracture (HR = 1.17, 95% CI = 0.96-1.43) with quetiapine than with risperidone. Dose-response relationships were observed for all events (HR = 1.12, 95% CI = 1.05-1.19 for high vs low dose for all events combined). CONCLUSION:These associations underscore the importance of carefully selecting the specific APM and dose and monitoring their safety, especially in nursing home residents who have an array of medical illnesses and are undergoing complex medication regimens.

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Instrumental variable applications using nursing home prescribing preferences in comparative effectiveness research.

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Instrumental variable applications using nursing home prescribing preferences in comparative effectiveness research.

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