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Comparative Study
. 2012 Jan;60(1):34-41.
doi: 10.1111/j.1532-5415.2011.03772.x. Epub 2011 Dec 8.

Prevalence of unplanned hospitalizations caused by adverse drug reactions in older veterans

Zachary A Marcum  1 , Megan E Amuan, Joseph T Hanlon, Sherrie L Aspinall, Steven M Handler, Christine M Ruby, Mary Jo V Pugh
Affiliations
Comparative Study

Prevalence of unplanned hospitalizations caused by adverse drug reactions in older veterans

Zachary A Marcum et al. J Am Geriatr Soc. 2012 Jan.

Abstract

Objectives: To describe the prevalence of unplanned hospitalizations caused by adverse drug reactions (ADRs) in older veterans and to examine the association between this outcome and polypharmacy after controlling for comorbidities and other patient characteristics.

Design: Retrospective cohort.

Setting: Veterans Affairs Medical Centers.

Participants: Six hundred seventy-eight randomly selected unplanned hospitalizations of older (aged ≥ 65) veterans between October 1, 2003, and September 30, 2006.

Measurements: Naranjo ADR algorithm, ADR preventability, and polypharmacy (0-4, 5-8, and ≥9 scheduled medications).

Results: Seventy ADRs involving 113 drugs were found in 68 (10%) hospitalizations of older veterans, of which 25 (36.8%) were preventable. Extrapolating to the population of more than 2.4 million older veterans receiving care during the study period, 8,000 hospitalizations may have been unnecessary. The most common ADRs that occurred were bradycardia (n = 6; beta-blockers, digoxin), hypoglycemia (n = 6; sulfonylureas, insulin), falls (n = 6; antidepressants, angiotensin-converting enzyme inhibitors), and mental status changes (n = 6; anticonvulsants, benzodiazepines). Overall, 44.8% of veterans took nine or more outpatient medications and 35.4% took five to eight. Using multivariable logistic regression and controlling for demographic, health-status, and access-to-care variables, polypharmacy (≥9 and 5-8) was associated with greater risk of ADR-related hospitalization (adjusted odds ratio (AOR) = 3.90, 95% confidence interval (CI) = 1.43-10.61 and AOR = 2.85, 95% CI = 1.03-7.85, respectively).

Conclusion: ADRs, determined using a validated causality algorithm, are a common cause of unplanned hospitalization in older veterans, are frequently preventable, and are associated with polypharmacy.

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Conflict of interest statement

Conflict of Interest

Authors JH and SH are employed by the VA Pittsburgh Healthcare System. Author SA is employed by the VA Center for Medication Safety. Author MJP is employed by the South Texas Veterans Health Care System. Author MA is employed by the Edith Nourse Rogers Memorial VA. Dr. Hanlon has received research funding from National Institute on Aging grants (R01AG027017, P30AG024827, T32AG021885, K07AG033174, R01AG034056), a National Institute of Mental Health grant (R34 MH082682), a National Institute of Nursing Research grant (R01NR010135), an Agency for Healthcare Research and Quality grant (R01HS017695) and from VA HSR&D IIR-06-062. Dr. Handler has received research funding from the Agency for Healthcare Research and Quality grants (R01HS018721, R18HS018151), a National Institute on Aging grant (K07AG033174), a Pennsylvania Department of Aging grant, and from VA HSR&D IIR-06-062. Dr. Pugh has received research funding from VA HSR&D DHI 09-237 (PI); VA HSR&D IIR-06-062 PI, Epilepsy Foundation PI, VA HSRD PPO 09-295 PI, VA HSR&D IIR 02-274 PI. Pugh as co-I: VA HSR&D IIR 08-274, VA HSR&D SDR-07-042, IIR-05-121, IAF-06-080, IIR-09-335, SHP 08-140, TRX 01-091 Department of Defense CDMRP 09090014, NIH R01-NR010828, Pugh Speaker Honoraria: 2009 Kelsey Seybold Research Foundation $400.

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