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Adverse Outcomes of High Risk Medication in Older Adult Veterans
Lund BC, Kaboli PJ. Adverse Outcomes of High Risk Medication in Older Adult Veterans. Paper presented at: VA HSR&D / QUERI National Meeting; 2015 Jul 9; Philadelphia, PA.
Clinical validation studies of prescribing quality measures are limited, often with conflicting results arising from methodological limitations. The objective was to determine whether one such metric, high risk medication in the elderly (HRME), is associated with adverse outcomes.
Using national VHA administrative data, veterans age > = 65 years in FY09 with regular VHA medication use and > = 1 primary care visit in the prior year were selected. The exposed group was comprised of new HRME starters; defined as a first prescription in FY09 preceded by 365 days with no HRME use. Controls were patients with no HRME use in FY09 where a random non-HRME prescription date served as the index date. Adverse outcomes included emergency department visit, inpatient hospitalization, or death within 90 days of index, using VHA plus merged Medicare data. General linear mixed models were used to express risk associated with HRME exposure, adjusted for patient characteristics and hierarchical clustering within clinics and medical centers.
The unadjusted frequency of adverse outcomes was 27.9% vs 16.2% in the HRME and control groups, respectively. New HRME exposure remained significantly associated with adverse outcomes after adjustment (OR: 1.67; 95% CI: 1.64, 1.71). This finding persisted across sensitivity analyses: 30-day adverse events (OR: 1.79; 95% CI: 1.74, 1.84), VHA events only (OR: 2.15; 95% CI: 2.10, 2.20), and substitution of non-HRME new drug starters as controls (OR: 1.67; 95% CI: 1.63, 1.70). In a separate analysis, we compared prevalent HRME users to non-user controls (OR: 1.34; 95% CI: 1.32, 1.35).
HRME exposure was associated with adverse outcomes in elder veterans across multiple sensitivity analyses. Risk associated with incident (new) HRME exposure (OR = 1.67) yielded a stronger effect size than prevalent HRME exposure (OR = 1.34). Future planned analyses will examine the stability of these findings using alternate methods, including propensity score matching and instrumental variables.
Most prior validation studies of HRME and other similar quality measures (e.g., Beers criteria) have examined prevalent drug exposure as opposed to incident (new) exposure, which may explain historic mixed findings. High risk medication use persists in VHA and is associated with adverse outcomes.