Participants
Registered nurses from two Norwegian hospitals with 2300 nurses, and three municipalities with 500 nurses were invited to participate in the survey. The invitation was announced in the institutions through the management line, and participants enrolled with their manager or directly with the researcher. Recruitment would be closed on reaching 200 participants.
Inclusion criteria were registered nurses with at least 1 year of work experience in a 50% part-time job or more. Nurses that were excluded were those working in outpatient clinics, those who did not administer drugs, and any who were not sufficiently fluent in Norwegian. The study was performed from September 2007 to April 2008.
Study design
The design was a cross-sectional study performed in classrooms under controlled conditions. The participants completed a form with relevant background characteristics and performed a multiple-choice (MCQ) test in pharmacology, drug management, and drug dose calculation. The maximum time for the test was 2.5 h.
Variables
Participant characteristics
The following background characteristics were recorded: age, gender, place where they grew up, place of education while studying nursing, length of work experience as a nurse in at least a 50% part-time job, employment fraction for the past 12 months, present place of work in a specific hospital department (surgery, internal medicine or psychiatry), or primary health care (nursing home or ambulatory care). In addition, further educational background was recorded: number of years of studying mathematics beyond the first mandatory year at upper secondary school; other education prior to nursing; postgraduate specialization; and further education or refresher courses in pharmacology, drug management, or drug dose calculation during the past 3 years. In addition, statements regarding sense of coping and self-esteem/wellbeing were recorded.
Medication knowledge and certainty
Medication knowledge was in this context used as a common term, including the disciplines of pharmacology (pharmacokinetics and dynamics), drug management (regulations, storage, preparation of drugs and administration to patients) and drug dose calculation, and each discipline consisted of different topics. The medication knowledge test was composed as a multiple-choice test, with 14 questions with 3-4 alternative answers within each discipline. The disciplines and topics were as follows (number of questions for each topic shown in brackets):
Pharmacology: general pharmacology (3), effects (3), side effects (3), administration formulas (2), interactions (1), and generic drugs (2).
Drug management: regulations (2), storage (4), dispensation (4), and administration (4).
Drug dose calculation: conversion of units (7), formulas for calculation of dose, quantity or strength (4), infusions (2), and dilutions (1).
The translated questions are given in Additional file 1.
To cover all the topics within each discipline, questions were put together from actual tests for bachelor nursing students at university colleges (drug dose calculation), from tests of continuing educational programs used in Norwegian hospitals, and a few questions were added based on experience from problems arising among nurses.
To assess the knowledge, the requirements to pass exams at the university colleges in Norway were used as a guideline. The limit to pass MCQ-tests is normally 60% correct answers, but for drug dose calculations, the requirement is a faultless test. For this study, nine out of 14 correct answers (64%) was chosen as the lowest acceptable score in pharmacology and drug management, and for drug dose calculations only a faultless test was accepted.
For each question, the participants indicated self-estimated certainty, graded from 0-3: 0 = very uncertain (would search for help, consult colleagues/reference books), 1 = relatively uncertain (would probably search for help), 2 = relatively certain (would probably not search for help), and 3 = very certain (would not search for help).
Risk of error
Risk of error was estimated by combining knowledge and certainty for each question, rated on a scale from 1 to 3 devised for this study. Correct answers combined with high certainty (relatively/very certain) was regarded as a low risk of error (score = 1), low certainty (relatively/very uncertain) independent of correct answer was regarded as a moderate risk of error (score = 2), and incorrect answer combined with high certainty (relatively/very certain) was regarded as a high risk of error (score = 3).
Sense of coping and self-esteem/wellbeing
Nine statements from General Health Questionnaire (GHQ 30), a Quality of life tool focusing on psychological and psychosocial symptoms, were used for the purpose of this study [16]. Five of the statements were related to coping (finding life a struggle; being able to enjoy normal activities; feeling reasonably happy; getting scared or panicky for no good reason; and being capable of making decisions), and four statements were related to self-esteem/wellbeing (overall doing things well; satisfied with the way they have carried out their task; managing to keep busy and occupied; and managing as well as most people in the same situation). The ratings of these statements were 0-3: 0 = more/better than usual, 1 = as usual, 2 = less/worse than usual, and 3 = much less/worse than usual; "as usual" was defined as the normal state.
Ethics
The Norwegian Data Inspectorate, represented by Privacy Ombudsman for Research at Oslo University Hospital, Ullevål, approved the collection of data for the study. All participants gave written informed consent. To protect the participants from any consequences as a result of the test, data were made anonymous before analysis.
Analyses
Comparisons between groups were analyzed with Chi-square/Fishers exact test, t-test/Mann-Witney U-test, ANOVA/Kruskal-Wallis and Pearson/Spearman tests for correlations depending on data distribution. The same tests were used for the study of associations between variables and medication knowledge, certainty and risk of error. Variables associated with medication knowledge, certainty and risk of error with p < 0.20 were included in stepwise forward linear regression analyses, corrected for age and gender, to find independent predictors. Two-tailed significance tests were used, and a p-value < 0.05 was considered statistically significant. The analyses were performed with SPSS version 13.0 (SPSS Inc., Chicago, IL, USA).
Studies testing drug dose calculation skills among nurses have shown a mean score of 75% (SD 15%), i.e. 10.5 (SD 2.1) in this study with a max score of 14 in each discipline [17–19]. This study, of 200 participants, has a power of 0.9 to detect a difference of one correct answer in two groups of the same size (p < 0.05), and was determined by the number needed for a subsequent randomized controlled study to compare two didactic methods in drug dose calculation.
Missing data were handled as described in the protocol: Unanswered questions in the medication knowledge test were scored as "incorrect answer," and unanswered certainty score as "very uncertain".