Table 1

Probabilities and SEs for base-case, one-way and probabilistic sensitivity analyses for estimating the cost of managing outpatients with influenza-like illness in Sri Lanka

Description of probabilityProbabilities (sensitivity analyses ranges) for each strategyDistribution applied in probabilistic sensitivity analysisSource*
Standard careClinical predictionTargeted testingUniversal testing
Clinical prediction
 Having high pretest probability of influenza0.15 (0.12–0.18)0.15 (0.12–0.18)BetaPhase I11
Having influenza
 Overall0.39 (0.35– 0.43)0.39 (0.35– 0.43)BetaAll11
 If high pretest probability of influenza0.60 (0.49–0.71)0.60 (0.49–0.71)BetaAll11
 If low pretest probability of influenza0.35 (0.31–0.40)0.35 (0.31–0.40)BetaAll11
Receiving antibiotic prescriptions
 If high pretest probability of influenza0.73 (0.63–0.83)†BetaAll11
 If low pretest probability of influenza0.78 (0.72–0.84)‡0.78 (0.72–0.84)‡BetaAll11
 If influenza positive, result known0.62 (0.51–0.74)0.62 (0.51–0.74)BetaPhase II12
 If influenza positive, result unknown0.83 (0.76-0.89)BetaPhase I12
 If influenza negative, result known0.76 (0.70–0.82)0.76 (0.70–0.82)BetaPhase II12
 If influenza negative, result unknown0.80 (0.74-0.87)BetaPhase I12
Test characteristics
 Sensitivity of rapid influenza test0.88 (0.84–0.93)0.88 (0.84–0.93)BetaAll11
 Specificity of rapid influenza test0.95 (0.93–0.98)0.95 (0.93–0.98)BetaAll11
  • Probabilities are presented for four strategies: standard care, clinical prediction, targeted testing for influenza and universal testing for influenza.

  • *The source of data indicates whether probabilities were extracted from phase I, phase II or the entire study (All) from which data are derived.

  • †Since the impact of the clinical prediction tool on antibiotic prescribing patterns is unknown, patients with a high pretest probability of influenza were estimated to have the probability of antibiotic prescriptions with a known positive rapid influenza test +0.5 * (difference in probability of receiving antibiotics with unknown vs known positive influenza test).

  • ‡Patients with a low pretest probability of influenza were estimated to have the probability of antibiotic prescriptions with a known negative rapid influenza test +0.5 * (difference in probability of receiving antibiotics with unknown vs known negative influenza test).