STOPP Criteria for Potentially Inappropriate Medications in Older People

Older people, particularly those presenting to a hospital with an acute illness, have a high rate of inappropriate medication use, according to researchers. Because of the risk of intolerance associated with adverse pharmacodynamics or pharmacokinetics or drug–disease interactions, some drugs are considered inappropriate for older patients. There are sets of criteria for determining which drugs are inappropriate in an older population, including the Beers criteria, developed in 1991, and revised in 1997 and 2003. The 2003 Beers criteria consist of 2 lists of drugs to be avoided in older people: drugs to be avoided independent of diagnosis and those to be avoided considering diagnosis. Results of studies examining use of medications defined by Beers criteria as potentially inappropriate in older persons have been mixed in establishing statistically significant associations with avoidable adverse drug events (ADEs). Two recent studies, 1 in the United States and 1 in Italy, found no significant link between Beers criteria potentially inappropriate medicines (PIMs) and ADEs. However, other studies have found an association between PIMs and ADEs. Noting that most studies to date have been limited by their retrospective design, researchers recently conducted a prospective study to determine whether PIMs defined by the STOPP (Screening Tool of Older Persons’ Potentially Inappropriate Prescriptions) criteria are significantly associated with ADEs in older persons with acute illnesses. Study results were reported in Archives of Internal Medicine [2011;171(11):1013-1019]. The study enrolled 600 consecutive patients ≥65 years of age admitted to a university teaching hospital with acute illness over a period of 4 months. Median age was 77 years, 40.2% (n=241) of the patients were male, 48.0% had a Charlson Comorbidity Index score of ≥2, and 19.5% had a history of chronic cognitive impairment. The researchers compared the proportions of patients taking Beers criteria PIMs and STOPP criteria PIMs with avoidable ADEs that were causal or contributory to hospital admission. There were a total of 4523 prescriptions for the 600 patients; median number per patient was 7; 34.0% were prescribed ≤5 daily regular prescription drugs, 46.0% were prescribed 6 to 10 daily drugs, and 20.0% were prescribed >10 daily drugs. Using STOPP criteria, researchers identified 610 PIMs in 337 patients (56.2% of all patients; 235 PIMs in 173 patients were identified using Beers criteria (28.8% of all patients). There were 329 ADEs identified in 26.3% (n=158) of the 600 patients. Of those, 10.9% (n=36) of the ADEs were determined to have been the primary cause of the index hospitalization; 55.6% (n=183) were determined to have been a clinically significant contributory factor to the index hospitalization, rather than the undisputed prime cause. In the 158 patients experiencing a clinically significant ADE, 66.6% (n=219) of the ADEs were either causal or contributory to the index hospitalization. Of those, 68.9% (n=151) were avoidable or potentially avoidable. Of the 329 ADEs, 51.5% (n=170) involved STOPP criteria PIMs compared with 20.4% (n=67) related to Beers criteria PIMs (P<.001); clinically significant ADEs were listed in STOPP criteria 2.54 times more often than in Beers criteria. Following adjustment for covariates, the likelihood of a serious avoidable ADE increased when STOPP PIMs were prescribed (odds ratio, 1.847; 95% confidence interval [CI], 1.506-2.264; P<.001). There was no significant increase in risk of ADEs when Beers criteria PIMS were prescribed (odds ratio, 1.276; 95% CI, 0.945-1.722; P=.11). Study limitations cited by the authors include lack of inclusion of nonprescription over-the-counter medications and the inability to determine the strength of the temporal relationship between the introduction of PIMs and the onset of ADE symptoms. In conclusion, the researchers noted, “criteria for PIMs are not meant to replace clinical judgment; rather, they are designed to enhance clinical evaluation of pharmacotherapy in older patients. Criteria for PIMs in older people should be of benefit for prevention of avoidable ADEs associated with prescription of such PIMs. The present data indicate that STOPP criteria meet this necessary requirement, whereas Beers criteria do not.”