BEST EVIDENCE TOPIC REPORTS Towards evidence based emergency medicine: best BETs from the Manchester Royal Infirmary

A short cut review was carried out to establish whether negative dipstick urine analysis is sensitive enough to rule out urinary tract infection (UTI) in adults with urinary symptoms. Altogether 75 papers were found using the reported search, of which two presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these best papers are tabulated. A clinical bottom line is stated. Clinical scenario A 20 year old student presents to the emergency department with a three day history of urinary frequency, dysuria, and lower abdominal pain. Examination is unremarkable and dipstick urine analysis is normal. You wonder whether normal dipstick urine analysis is sufficient to rule out a UTI or whether antibiotics anyway should be prescribed whatever the result. Three part question In [adults with symptoms of a urinary tract infection] does [negative dipstick urine analysis] rule out a [UTI]? Search strategy Medline 1966–04/03 using the OVID interface. [(exp Urinalysis OR exp Indicators and Reagents OR exp Reagent Strips OR stix.af OR urinalysis.af) AND (exp Urinary Tract Infections OR (urin$ adj5 infect$).af OR UTI.af OR exp Bacteriuria OR bacteriur$.af) AND (dysuria.af OR frequency.af OR haematuria.af OR hematuria.af OR stranguria.af OR urgency.af)] LIMIT to human AND English language AND all adult <19 plus years> Search outcome Altogether 75 papers were found. Of these, two were identified as answering the three part question. One of these was a meta-analysis containing nine papers not identified by the original search as they did not consider dipstick urine analysis (table 1). Comment(s) The meta-analysis shows that the prevalence of UTI in patients who present with symptoms of UTI is around 50%. The probability of UTI is even higher (around 90%) with a convincing history. Dipstick urine analysis is a quick and inexpensive test however sensitivity (and therefore negative Best evidence topic reports (BETs) summarise the evidence pertaining to particular clinical questions. They are not systematic reviews, but rather contain the best (highest level) evidence that can be practically obtained by busy practising clinicians. The search strategies used to find the best evidence are reported in detail in order to allow clinicians to update searches whenever necessary. The BETs published below were first reported at the Critical Appraisal Journal Club at the Manchester Royal Infirmary or placed on the BestBETs web site. Each BET has been constructed in the four stages that have been described elsewhere. The BETs shown here together with those published previously and those currently under construction can be seen at http://www.bestbets.org. Five BETs are included in this issue of the journal together with another five that inform the accompanying accumulator BET. c Accuracy of negative urine analysis in ruling out urinary tract infection in adults c Venous blood gas in adult patients with diabetic ketoacidosis c Antithrombotic treatment of below knee deep venous thrombosis c Buccal nitrates in left ventricular failure c Oral methionine compared with intravenous n-acetyl cysteine for paracetamol overdose