[Insert Table 1 here]

Risk factors for drug-related readmissions

In the trial population, 582 (22%) patients experienced one or more drug-related readmissions within 12 months after hospital discharge. Sixteen risk factors (HR > 1) and three protecting factors (HR < 1) for experiencing a drug-related readmission were identified (Figure 1). Risk factors were related to age, previous hospital visits, cardiovascular, liver, lung and peptic ulcer disease in medical history, multimorbidity (i.e., higher Charlson Comorbidity Index score), number of medications upon admission and cardiovascular or lung disease as discharge diagnosis. The individual risk factors with the highest HRs were previous liver disease (HR 2.46, 95% CI 1.15–5.24), ischaemic heart disease as discharge diagnosis (HR 2.06, 95% CI 1.32–3.21) and previous peptic ulcer disease (HR 1.86, 95% CI 1.10–3.14). Protecting factors were previous dementia diagnosis (HR 0.55, 95% CI 0.39–0.78), and urinary tract infection (HR 0.60, 95% CI 0.39–0.92) and injuries, intoxications and other complications of external factors (HR 0.50, 95% CI 0.31–0.83) as discharge diagnosis. Twelve risk factors and two protecting factors were associated with all-cause readmissions (Supporting Information S3, Figure A). The risk factor with the highest HR was tumour as discharge diagnosis (HR 2.33, 95% CI 1.69–3.22). Five risk factors for experiencing an all-cause ED visit were identified, with one or more ED visits 12 months prior to admission having the highest HR (1.71, 95% CI 1.51–1.94; Supporting Information S3, Figure B).