The patterns and burden of multimorbidity in geriatric patients with prolonged use of addictive medications

Background Multimorbidity and prolonged use of addictive medications are prevalent among older patients, and known to increase the risk of adverse drug events. Yet, the relationship between these two entities has remained understudied. Aims This study explored the association between multimorbidity burden and prolonged use of addictive medications in geriatric patients, adjusted for clinically important covariates. Furthermore, we identified comorbidity patterns in prolonged users. Methods We conducted a cross-sectional study on a consecutive sample of 246 patients, aged 65–90 years, admitted to a large public university hospital in Norway. We defined prolonged use of addictive medications as using benzodiazepines, opioids and/or z-hypnotics beyond the duration recommended by clinical guidelines (≥ 4 weeks). Multimorbidity was assessed with the Cumulative Illness Rating Scale for Geriatrics (CIRS-G), based on diagnoses made by independent physicians. Results Compared to non-prolonged use, prolonged use was significantly more common among patients who had psychiatric (19/27, 70%), liver (19/22, 86%), upper gastrointestinal tract (21/32, 66%), musculoskeletal (52/96, 54%), or nervous system disorders (46/92, 50%). Patients with prolonged use had a higher multimorbidity burden than those without such use (CIRS-G score, mean = 7.7, SD = 2.7 versus mean = 4.6, SD = 2.2, p < 0.001). Multivariable logistic regression indicated a significant association between multimorbidity burden and prolonged addictive medication use (OR = 1.72, 95% CI 1.42–2.08). Predictive margins postestimation showed a systematic increase in the predicted CIRS-G scores when the number of addictive drug used increases. Conclusions Multimorbidity is strongly associated with prolonged use of addictive medications. Multiple substance use may aggravate disease burden of older patients.