Prevalence, nature and predictors of omitted medication doses in mental health hospitals: a multi-centre study

Richard N. Keers, Mark Hann, Ghadah H. Alshehri, Karen Bennett, Joan Miller, Lorraine Prescott, Petra Brown, Darren M. Ashcroft

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Background: Whilst the burden and nature of omitted medication doses in general hospitals is now better understood, in-depth evidence from mental health hospitals is limited which could severely limit improvement efforts in this unique setting.
Objective: Determine the prevalence, nature and predictors of omitted medication doses affecting inpatients in two English National Health Service (NHS) mental health trusts.
Setting: Two NHS trusts: twenty seven adult and elderly wards across 9 hospitals.
Method: Over 6 data collection days spanning a 3 month period trained pharmacy teams screened inpatient prescription charts for scheduled and omitted medication doses. Data were collected for inpatients admitted up to two weeks prior to each data collection day. Omitted doses were classified as ‘time critical’ and ‘preventable’ based on established criteria. Multilevel logistic regression analyses using STATA v15® determined the effects of ward, medication and patient factors on the likelihood of omitted dose occurrence.
Main outcome measure: Omitted dose rates were presented as frequencies with 95% confidence intervals (CI) and omitted dose risks as adjusted odds ratios (OR) with 95% CI.
Results: 18,664 scheduled medication doses were screened for 444 inpatients and 2,717 omissions were identified, giving a crude rate of 14.6% (95% CI 14.1-15.1). The crude rate of ‘time critical’ omitted doses was 19.3% (95% CI 16.3-22.6%). ‘Preventable’ omitted doses comprised one third of all omissions (34.5%, 930/2694). Logistic regression analysis revealed that medicines affecting the central nervous system were 55% less likely to be omitted compared to all other medication classes (9.9% vs. 18.8%, OR 0.45 (0.40-0.52)) and that scheduled doses administered using non-oral routes were more likely to be omitted compared the oral route (inhaled OR 3.47 (2.64-4.57), topical 2.71 (2.11-3.46), ‘other’ 2.15 (1.19-3.90)). ‘Preventable’ dose omissions were more than twice as likely to occur for ‘time critical’ medications than non-time critical medications (50.4% vs. 33.8%, OR 2.24 (1.22-4.11)).
Conclusion: Omitted medication doses occur commonly in mental health hospitals with ‘preventable’ omissions a key contributor to this burden. Important targets for remedial intervention have been identified which should be used to guide efforts to minimise dose omission in mental health settings.
Original languageEnglish
JournalP L o S One
Early online date6 Feb 2020
Publication statusPublished - 6 Feb 2020


  • Medication errors
  • hospitals
  • medicines administration
  • omitted dose
  • mental health
  • psychiatry


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