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 probability Probabilities (sensitivity analyses ranges) for each strategy Distribution applied in probabilistic sensitivity analysis Source* Standard care Clinical prediction Targeted testing Universal testing Clinical prediction Having high pretest probability of influenza – 0.15 (0.12–0.18) 0.15 (0.12–0.18) – Beta Phase I11 Having influenza Overall 0.39 (0.35– 0.43) – – 0.39 (0.35– 0.43) Beta All11 If high pretest probability of influenza – 0.60 (0.49–0.71) 0.60 (0.49–0.71) Beta All11 If low pretest probability of influenza – 0.35 (0.31–0.40) 0.35 (0.31–0.40) Beta All11 Receiving antibiotic prescriptions If high pretest probability of influenza – 0.73 (0.63–0.83)† – Beta All11 If low pretest probability of influenza – 0.78 (0.72–0.84)‡ 0.78 (0.72–0.84)‡ Beta All11 If influenza positive, result known – – 0.62 (0.51–0.74) 0.62 (0.51–0.74) Beta Phase II12 If influenza positive, result unknown 0.83 (0.76-0.89) – – Beta Phase I12 If influenza negative, result known – – 0.76 (0.70–0.82) 0.76 (0.70–0.82) Beta Phase II12 If influenza negative, result unknown 0.80 (0.74-0.87) – – Beta Phase I12 Test characteristics Sensitivity of rapid influenza test – – 0.88 (0.84–0.93) 0.88 (0.84–0.93) Beta All11 Specificity of rapid influenza test – – 0.95 (0.93–0.98) 0.95 (0.93–0.98) Beta All11
• 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).