Point of care tests Presentation , Nordisk kongress København Morten Lindbæk, professor University of Oslo and ASP

Outline  C-reactive protein  How often used  Does CRP contribute to better diagnosis?  Does CRP contribute to lower antibiotic prescription?  More use in outpatient care – nursing homes?  Strep-test  Future tests - Procalcitonin?  Does use of POC-testing contribute to medicalising self-limiting RTIs?

CRP – how often used?  Norway: 1.8 mill/13 mill.(14%) of all consultations in primary care per year, started in 1990, reimbursed, now patient pays half.  Vestfold Winter 2003: 44% of all with RTIs  Sweden: 31%-41% of consultations with RTIs in general practice  Denmark: Also extensively used.  Finland: Much lower us in primary care  Holland: Little use  UK: no use in primary care  Switserland: moderate use in primary care

Does CRP contribute to better diagnostic work in general practice  LRTI  Van der Meer: syst review of diagnostic value: 12 studies, heterogenous, sens 8-99%, spec 27-95% bact. infection. Conclusion: Not recommended. Much discussed  Hopstaken (Holland) demonstrated that CRP was good to single out patients with documented viral/bacterial infection, not to separate them  Melbye demonstrated that CRP was good to single out patients with bacterial pneumonia in primary care  Acute sinusitis  Jens G Hansen BMJ 1995 (Both CRP and ESR)  Lindbæk (CRP/ESR bivariate, only ESR multivariate analysis)  Tonsillitis?  Can CRP single out those Strep A patients that can profit from antibiotic treatment? Not been performed research on this

Can use of CRP contribute to more rational antibiotic use in RTIs?  Acute sinusitis:  Bjerrum Doctors using CRP prescribed in 59%, without 78%  JG Hansen: RCT based on elevated CRP-level, demonstrated significant less pain, but not general condition  LRTIs:  Cals Dutch study (BMJ May 09). 2x2 factorial design with educational outreach (27% vs 54%) and use of CRP (31% vs 53%). Both gave significant lowering of prescription, 23% in combination  RTIs:  Lindbæk observational study CRP test contributed significantly to 30% of patients with infections. CRP contributed to reduction of antibiotics in 25%

Other use of CRP-test in outpatient care  The use in nursing homes in Norway is increasing. Can contribute to better diagnosing of RTI’s. Especially combined with more use of intravenous antibiotics  Also more use in homebased care by nurses

Can use of Strep A test contribute to more exact diagnosis?  Sensitivity 90%, specificity 95%, LR+ 16  Combination of Centor criteria (4) and testing gives most certain diagnosis  But high rate of healthy carriers, especially among children and adolescents in summer, % (Ronny Gunnarson)

Can use of Strep A test contribute to reduced use of antibiotics?  No significant results from primary care, one smaller Danish study showed no reduction (Andersen et al BMJ 1995)  Some studies from specialist care, pediatricians in Greece

New promising POC-test:Maybe procalcitonin?  METHODS: 53 Swiss primary care physicians recruited 458 patients, each patient with an acute respiratory tract infection and, in the physician's opinion, in need of antibiotics. Results after 2-4 hours from hospital  RCT: For patients randomized to procalcitonin-guided therapy or standard, the use of antibiotics was more or less strongly discouraged or recommended (cut-off >0.25 microg/L).  RESULTS: With procalcitonin-guided therapy, the antibiotic prescription rate was 72% lower (95% CI, 66%- 78%) than with standard therapy. Both approaches led to a similar proportion of patients reporting symptoms of ongoing or relapsing infection at 28 days (adjusted odds ratio, 1.0 [95% CI, ]).

Medicalising effect of POC-testing?  Malin Andre: Question the use of CRP, 42% of all with RTI had a test performed.  Often used in URTI where the agent often is viral and the consequence is doubtful. Small reduction in ab us (44% vs 41%). Danger of medicalisation  Will use of POC-testing lead to: Patients/parents go to doctor just to be sure?  ”Table catching”: When you have taken a strep A, positive, it is harder to avoid giving antibiotics, even if the patient is feeling pretty well  Should GPs be more critical in when to use POC-tests. Reimbursement?