Laboratory tests in out-of-hours services in Norway. Studies with special emphasis on use and consequences of C-reactive protein test in children

Abstract

Background: Children with infections and respiratory symptoms have the highest contact rate with Norwegian out-of-hours (OOH) services, especially in the youngest age group, and during the winter season. Many contacts are non-urgent in a strict medical sense. Onsite measurement of C-reactive protein (CRP) is the most frequent laboratory test in Norwegian OOH, used in 60% of all contacts with children with infections and respiratory diseases. The aim of CRP is to differentiate between bacterial infections, viral and/or non-serious infections and to keep the use of antibiotics as low as possible. Nevertheless, the use of antibiotics has increased since the test was introduced as a point of care test until 2013. Several studies have investigated the diagnostic value of laboratory tests for children with fever, but not in primary health care where the prevalence of serious bacterial infections is low. Objective: Investigate the use of laboratory tests at Norwegian out-of-hours services and which characteristics of the doctor, patient, diagnoses and geography that affects it. Compare the RGPs’ rate of CRP use at daytime and at OOH in consultations with children. Evaluate if pre-consultation CRP screening affects the choice of treatment Identify predictors for prescription of antibiotics and referral to hospital for children at OOH services. Design/method: The first and second papers are from two cross-sectional registry based studies, based on electronic compensation claims from consultations in primary care. The third study (third paper) was a randomized controlled observational study at OOH-services in Norway, including children < 7 years, presenting fever and/or respiratory symptoms to an OOH-service or a paediatric emergency unit. Every third child was randomized to a CRP test before the consultation, for the rest CRP was taken at request. The data consists of clinical examination results and questionnaire to parents. The fourth paper is an observational study based on data from the same study. Results: Paper I: A CRP test is administered in 31% of all consultations OOH, for children with respiratory infections in 55%. Young doctors and doctors at central OOH services use the test most often. Paper II: All RGPs use the CRP test more frequently OOH than in daytime practice; moreover, a high use at daytime indicates a high use OOH. Paper III: In the group pretested with CRP, the antibiotic prescription rate was 26%, compared with 22% in the control group, there was no significant difference. Predictors for ordering a CRP test were a high fever at the consultation and the parents’ opinion that their child needed antibiotics. Paper IV: Main predictors for prescription of antibiotics were CRP values > 20 mg/L, signs on ear examination and use of paracetamol during the previous 24 hours. A high respiratory rate, low oxygen saturation and signs of auscultation were predictors for referral to hospital. In addition, parents’ assessment of the seriousness was significantly associated with prescription of antibiotics and referral to hospital. Conclusion: Paper I and II: CRP is extensively used at Norwegian OOH services and the differences in use cannot be explained by different diagnoses. Paper III: CRP screening of children with fever or respiratory symptoms will not reduce the prescription of antibiotics. Paper IV: Predictors for prescription are signs on ear examination, slightly elevated CRP values and the parents’ assessment. Disturbed respiration is the most important sign predicting hospital admission.