Researchers from Liverpool and Bangor Universities in the UK reported on their prospective observational study in which they looked at all hospital medical admissions of more than a 24-hour stay over a period of one month to explore the impact of ADRs on admissions.

Of the 1187 admissions during the month of the study, 218 were associated with ADRs. In some cases, one patient had more than one ADR; there were 235 in total. Only 10.1% of the ADRs were coincidental findings, meaning that the remainder were the primary cause of admission (66.5%) or a contributing factor (23.4%). 

See the full report on the BMJ website.