Validation of a Decision Aid to Assist Physicians in Reducing Unnecessary Antibiotic Drug Use for Acute Cystitis

Abstract

Background: In a previous study, use of a decision aid based on 4 clinical items would have reduced unnecessary antibiotic prescriptions for acute cystitis by 30% compared with usual physician care. Methods:We assessed the decision aid in a different population of females seen in community-based practice. Between April 7, 2002, and March 20, 2003, 225 Canadian family physicians recorded clinical findings, urine dip test results, and treatment decisions for 331 females with suspected cystitis. The number of decision aid items present was determined for each patient, and the sensitivity and specificity of decision aid recommendations for empirical antibiotics were determined using the gold standard of a positive urine culture result (Ն10 2 colony-forming units per milliliter). Total antibiotic prescriptions, unnecessary prescriptions (for negative culture results), and recommendations for urine cultures were determined and compared with physician management.Results: Three of the original decision aid variables (dys-uria, the presence of leukocytes [greater than a trace amount], and the presence of nitrites [any positive]) were associated with having a positive urine culture result (P Յ.001), but 1 variable (symptoms for 1 day) was not (P =.96). A simplified decision aid incorporating the 3 significant variables (empirical antibiotics without culture if Ն2 variables present; otherwise obtain a culture and wait for results) had a sensitivity of 80.3% (167/ 208) and a specificity of 53.7% (66/123). Following decision aid recommendations would have reduced antibiotic prescriptions by 23.5%, unnecessary prescriptions by 40.2%, and urine cultures by 59.0% compared with physician care (PϽ .001 for all). Conclusion:A simple 3-item decision aid could significantly reduce unnecessary antibiotic drug prescriptions and urine culture testing in females with symptoms of acute cystitis.

Sensitivity and specificity of urinalysis samples in critically ill patients

“…The combination of leukocyte esterase and urinary nitrite could be used as an accurate, robust indicator for positive bacteria cultures. For other measures, pyuria with WBCs >5 per hpf was 72.7% sensitive for culture positivity, which is also within the range of 69% to 90% sensitivity as previously reported [6,10]. We found that bacteriuria was 92.9% specific, within the range of 89% to 94% from prior studies [6].…”

Validating the prediction of lower urinary tract infection in primary care: sensitivity and specificity of urinary dipsticks and clinical scores in women

“…16,18 The validation study by McIsaac et al, which combined clinical information and dipstick results (two or more of dysuria, leucocytes, and nitrites) did not weight these variables, did not use dipstick haematuria, and demonstrated modest predictive values (LR +ve test = 1.73 and LR -ve test = 0.43). 16 This supports the present authors' previous findings that clinical information is unlikely to add greatly to the predictive value when all three predictive variables from dipsticks are used. 19 The study by Hummers-Pradier et al had similar limitations (it did not use dipstick haematuria, did not weight variables, and had no separate derivation and validation samples) and also found modest predictive values.…”

“…9,11,14-18 they have either not assessed the independent value of dipstick results and symptoms (hence potentially over-complicating clinical decision rules); and/or not used the range of dipstick variables (most include nitrite and leucocyte but not blood); and/or failed to develop and then test algorithms in separate samples (McIsaac et al being the exception 16 ); and/or had low power. Only the most recent dipstick studies have used the recent more rigorous laboratory guidelines for diagnosis.…”

“…Only the most recent dipstick studies have used the recent more rigorous laboratory guidelines for diagnosis. 16,18 The current authors have reported a study where a clinical score and a dipstick score were developed for women presenting with suspected UTI. 19 The independent predictive values of symptoms and of dipsticks results were assessed.…”

Diagnostic approach to urinary tract infections in male general practice patients: a national surveillance study

“…For females suspected of UTI, clinical decisions based on a diagnostic algorithm have been compared with care as usual by McIsaac et al 15 In their algorithm, antimicrobial prescription was recommended when at least two of the following clinical findings were present in females suspected of having a UTI: symptoms for 1 day, dysuria, positive leukocyte or nitrite test. The number of prescriptions in the case of a negative culture result could be reduced by 40% if their algorithm was implemented.…”