title: Pro re nata (as needed) medication in nursing homes: the longer you stay, the more you get?
abstract: OBJECTIVE
  Injudicious pro re nata (PRN) or as needed prescribing can lead to polypharmacy, potentially harmful drug interactions and total drug doses exceeding the maximum recommended. Despite the known risks and the widespread administration, there is a paucity of current research examining the use of PRN drugs in nursing homes. Therefore, we examined characteristics of PRN drug use and potential predictors in nursing homes.
  
  
  METHODS
  The multicentre cross-sectional study included a heterogeneous sample of 21 nursing homes in Northwestern Germany comprising 852 residents. Descriptive statistics and multivariable regression models were used to analyse and present the collected data.
  
  
  RESULTS
  Nearly three quarters (74.9 %) of all residents were treated with at least one PRN medication. On average, each resident was prescribed 2.5 ± 2.3 PRN drugs. On average, residents with no PRN prescriptions stayed since 2.4 ± 2.9 years in the nursing home. Residents with five and more PRN prescriptions were on average since 4.8 ± 4.3 years in the nursing home. In a multivariable analysis, length of stay above the median of 2.1 years (OR 2.4; 95 % CI 1.8, 3.2) and polypharmacy with five or more long-term drugs (OR 2.1; 95 % CI 1.5, 2.9) were associated with a higher number of PRN prescriptions. Most commonly used PRN drug was acetaminophen, which was prescribed to 289 (33.9 %) residents.
  
  
  CONCLUSIONS
  The high prevalence of PRN medication should be taken into account when considering polypharmacy and inappropriate drug prescribing or using screening tools like the STOPP/START (screening tool of older persons' potentially inappropriate prescriptions/screening tool to alert doctors to right) criteria in nursing homes. Physicians should regularly reconsider the need of each PRN drug on the medication schedule. Moreover, the high prevalence of PRN medication and the association with length of stay highlights the importance of an accurate documentation.
authors.affiliation: Department of Health Services Research, Carl von Ossietzky University Oldenburg, Ammerländer Heerstrasse 140, 26111, Oldenburg, Germany. michael.doerks@uni-oldenburg.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Dörks
authors.affiliation: Institute for Public Health and Nursing Science, Department for Health Services Research, University of Bremen, Bremen, Germany.
authors.forename: Guido
authors.initials: G
authors.lastname: Schmiemann
authors.affiliation: Department of Health Services Research, Carl von Ossietzky University Oldenburg, Ammerländer Heerstrasse 140, 26111, Oldenburg, Germany.
authors.forename: Falk
authors.initials: F
authors.lastname: Hoffmann
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D004363:Drug Utilization / Q000706:statistics & numerical data*; D005260:Female; D005858:Germany; D006801:Humans; D057970:Inappropriate Prescribing / Q000706:statistics & numerical data; D007902:Length of Stay; D008297:Male; D009735:Nursing Homes / Q000706:statistics & numerical data*; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*
keywords: Nursing home; Older people; Polypharmacy; Pro re nata (as needed) drug use