EVIDENCE-BASED ANSWER
Healthy, nonpregnant women presenting with the triad of frequency, dysuria, and no vaginal symptoms have about a 96% chance of having an urinary tract infection (UTI) (positive likelihood ratio [LR+]=24.6). Since no urinalysis result would substantially change the high likelihood of disease for these patients, empiric therapy is appropriate (strength of recommendation [SOR]: B).
A triage system based only on having 1 or more urinary symptoms is more sensitive but less specific: the chance of having a UTI drops to 50% (LR+=19). While empiric therapy is still likely to be appropriate, rates of false positives and inappropriate antibiotic use may rise (SOR: B).
Empiric treatment by telephone may also be considered (SOR: C). While no studies have specifically addressed the diagnostic value of UTI symptoms reported by phone, no increase in pyelonephritis or other adverse events has been seen with telephone treatment protocols. And while telephone treatment protocols can increase the use of guideline-recommended antibiotics and decrease costs, they may increase unnecessary antibiotic use overall. Contraindications to empiric therapy are listed in TABLE 1.
CLINICAL COMMENTARY
Telephone protocol for UTI reduces unnecessary office visits and lab testing
Robert Bonacci, MD
Mayo Clinic, Rochester, Minn
We have 10 years of experience with a telephone treatment protocol we developed for uncomplicated UTI; it has since been adopted by the Institute for Clinical Systems Improvement (ICSI). The protocol reduces unnecessary office visits and lab testing. We believe the protocol actually increases our prescribing of preferred first-line antibiotics for UTI. While it is convenient for our patients, its use has resulted in patients wanting to be treated over the phone even if they have “failed” the protocol. Overall, our patients are thankful we have a telephone protocol for uncomplicated UTI. We enjoy the use of a handful of other telephone protocols and hope to move toward web-based protocols in the future.
TABLE 1
Contraindications to empiric antibiotics for urinary tract infection (telephone treatment)
| Vaginal discharge |
| Prolonged symptoms |
| Severe or intolerable flank, side, or abdominal pain |
| Inability to urinate for more than 4 hours |
| Body temperature higher than 38.1°C (100.5°F) with flank pain, chills, nausea, or abdominal pain |
| Pregnancy |
| Recent urologic surgery, procedure, or bladder catheterization; UTI within the last 6 weeks or frequent UTI (≥3 times) in the last 12 months |
| Any symptoms that warrant urgent office-based evaluation according to the clinician |
| Adapted from Vinson and Quesenberry, Arch Intern Med 2004.6 |
Evidence summary
An evidence-based review1 found 5 high-quality studies on the diagnosis of acute uncomplicated UTI among women. (“Uncomplicated” was defined as normal urinary tract and no contributing medical problems, such as diabetes, neurogenic bladder, renal stones.) UTIs were defined as the presence of significant bacteriuria (≥104 to 105 colony-forming units) on culture. A patient presenting to a clinician with 1 or more UTI symptoms had approximately a 50% chance of having significant bacteriuria on culture.1 The authors estimated the pretest probability of UTI as 5% from the incidence of asymptomatic bacteriuria among healthy women.1,2 This produced a LR+ of 19 simply for presenting to a clinician with 1 or more UTI symptoms.1 The summary LRs for clinical signs and symptoms in the prediction of UTI after presentation to the office are found in TABLE 2. A history of a vaginal discharge or irritation has a LR– of 0.3, decreasing the probability of UTI for a patient presenting to the office from approximately 50% to 20%, so further testing would be indicated.1
No single sign or symptom accurately predicted UTI. However, the triad of dysuria with frequency but without vaginal symptoms increased the probability of significant bacteriuria on culture from 50% to 96% (LR+=24.6).1 In contrast, a 1999 review of 51 studies calculated that if both the nitrites and leukocyte esterase are positive on urine dipstick testing, the LR+ is 4.2; if both are negative the LR– is 0.3.1,3 Since the probability of UTI for patients with the symptom triad is so high, dipstick urinalysis is unlikely to alter management regardless of whether nitrites and leukocyte esterase were both positive or negative (posttest probability=98%–99% and 80%, respectively). If urine dipstick or other office-based tests are not needed to make the diagnosis of uncomplicated UTI for a patient with the classic triad of symptoms, then telephone treatment based on symptoms may be reasonable. Women who have recurrent UTIs (2 or more culture positive UTIs over the previous 12 months) can accurately self-diagnose subsequent UTIs based on symptoms (LR+=4.0).4,5