Family Practice Vol. 21, No. 2, 221-222
Family Practice Vol. 21, No. 2 © Oxford University Press 2004, all rights reserved.
Correspondence |
Managing acute cystitis in women
Tayside Centre for General Practice, University of Dundee, Kinsty Sample Way, Dundee DD2 4AD, UK
E-mail: t.p.fahey{at}dundee.ac.uk
We thank Anders Baerheim for his interest in our paper.1 We would like to address some of the points he raises.
There is still considerable uncertainty as to the prior probability of urinary tract infection (UTI) (-defined as a colony count of 
105 colony-forming units (c.f.u.)/ml) in women consulting in primary care. Reported priors have ranged between 12 and 59%.2 The true prior is critically important, as positive likelihood ratios in our and more recent studies of individual symptoms and signs are no higher than 2.1,3,4 If single symptoms and signs are used as a diagnostic guide, post-test probabilities are not raised substantially, certainly not into the treatment range.5 For this reason, clinical practice guidelines recommend that combined symptoms and signs are assessed in each patient (which have more powerful diagnostic test properties to raise or lower the post-test probability of UTI) allied with the use of near patient dipstix tests if after taking a history and examining a patient, post-test probability of UTI is intermediate.2,4 We agree with this diagnostic strategy, acknowledging that this approach needs to be validated in randomized trials assessing its impact on prescribing practice and clinical outcome.
We agree that our ‘gold standards’ of 105 c.f.u./ml and re-consultation within 1 month are imperfect and clearly describe their limitations in the discussion section of our paper.1 Two different ‘gold standards’ were used as a pragmatic means to assess alternative but related end points: laboratory diagnosis and clinical outcome.
Like others, we think empirical treatment on the basis of individual symptoms and signs exposes patients to unnecessary antibiotics.4 Attendant problems of medicalization, cost, contraceptive failure, side effects and antibiotic resistance are not trivial. There is good evidence that antibiotics are effective in reducing symptoms and duration of illness in women with UTI.6 Antibiotics should be prescribed to those patients with the highest probability of bacterial infection: clinical prediction rules incorporating symptoms, signs and (if necessary) near patient dipstix test results are the most rational way of achieving this aim.
References
1 Fahey T, Webb E, Montgomery AA, Heyderman RS. Clinical Management of urinary tract infection in women: a prospective cohort study. Fam Prac 2003; 20: 1–6.
2 Bent S, Nallamothu BK, Simel DL, Fihn SD, Saint S. Does this woman have an acute uncomplicated urinary tract infection? J Am Med Assoc 2002; 287: 2701–2710.
3 Medina-Bombardo D, Segui-Diaz M, Roca-Fusalba C, Llobera J. What is the predictive value of urinary symptoms for diagnosing urinary tract infection in women? Fam Prac 2003; 20: 103–107.
4 Mclssac W, Low DE, Bringer A, Pimlott N, Evans M, Glazier R. The impact of empirical management of acute cystitis on unnecessary antibiotic use. Arch Intern Med 2002; 162: 600–605.
5 Black ER, Bordley D, Tape TG, Panzer RJ. Diagnostic Strategies of Common Medical Problems. Philadelphia: American College of Physicians; 1999.
6 Christiaens TCM, De Meyere M, Verschraegen G, Peersman W, Heytens S, De Maeseneer JM. Randomised controlled trial of nitrofurantoin versus placebo in the treatment of uncomplicated urinary tract infection in adult women. Br J Gen Prac 2002; 52: 729–734.[ISI][Medline]
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