(HealthDay News) – The likelihood of unplanned admission is increased with polypharmacy, but the association is modified by the number of long-term conditions, according to a study published online Jan. 16 in the British Journal of Clinical Pharmacology.

Rupert A. Payne, MB, ChB, PhD, from the University of Cambridge in the United Kingdom, and colleagues linked Scottish primary care data from 180,815 adults with long-term clinical conditions and numbers of regular medications with national hospital admissions data for the following year. The correlation between prescribing and unplanned admissions was assessed for patients with different numbers of long-term conditions.

The researchers found that admission was more common for patients on multiple medications, but the risk of admission varied with the number of conditions. For patients with one condition, the odds ratio (OR) for unplanned admission was 1.25 for 4–6 vs. 1–3 medications (95% confidence interval [CI], 1.11–1.42), and 3.42 for >10 vs. 1–3 medications (95% CI, 2.72–4.28). For patients with multiple conditions, this effect was reduced, with no significant difference for patients with six or more conditions on 4–6 vs. 1–3 medications (OR, 1; 95% CI, 0.88–1.14) and a modestly increased likelihood of unplanned admission for those taking 10 or more medications (OR, 1.5; 95% CI, 1.31–1.71).

“This study provides powerful evidence that the number of regular medications is strongly associated with hospital admission,” the authors write. “However, the effect is much reduced in patients with multiple conditions, in whom only the most extreme levels of polypharmacy are associated with an increase in unplanned hospitalization.”

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