.80, 95 % CI 2.25-6.55). START criteria identified a total of 303 PPO in 170 (41.8 %) subjects. The risk of PPO increased by 60 % for every additional point in the Charlson Comorbidity Index (OR 1.60, 95 % CI 1.35-1.91). Polypharmacy also independently predicted the odds of at least one PPO according to START criteria (OR 2.19, 95 % CI 1.36-3.55).