A systematic review with nine studies and 1144 patients was abstracted in DARE . The number of patients in the studies ranged from 39 to 215. Four studies employed clinical examination, with two of these also employing ultrasound or X-ray. Six studies employed ultrasound, five of these in conjunction with X-ray and the sixth with clinical examination.
The prevalences of sinusitis varied from 0.26 to 0.80, with the majority in the range 0.5 to 0.6. The lowest prevalences were found in general practice, where the lowest sensitivities were also found (0.54 to 0.63). The sensitivities ranged from 0.61 (specificity 0.98) to 0.93 (specificity 0.62) for radiography, from 0.54 (specificity 0.94) to 0.94 (specificity 0.72) for ultrasound, and from 0.44 (specificity 0.66) to 0.48 (specificity 0.75) for clinical examination. The summary weighted mean sensitivities and specificities were, respectively: for radiography (7 studies, 996 sinuses), 0.87 (95% CI: 0.85, 0.88) and 0.89 (95% CI: 0.88, 0.91); for ultrasound (7 studies, 940 sinuses), 0.85 (95% CI: 0.84, 0.87) and 0.82 (95% CI: 0.80, 0.83); and for clinical examination (2 studies, 245 sinuses), 0.69 (95% CI: 0.65, 0.73) and 0.79 (95% CI: 0.75, 0.82). It was observed that there were differences in the sensitivity of radiography between hospital-based studies and those in primary care; the sensitivity was lower in primary care. The summary weighted positive and negative LRs were, respectively: for radiography, 3.36 (range: 2.43 to 29.83) and 0.26 (range: 0.11 to 0.52); for ultrasound, 2.78 (range: 1.30 to 9.94) and 0.30 (range: 0.08 to 0.74); and for clinical examination, 3.25 (range: 3.13 to 3.45) and 0.40 (range: 0.32 to 0.43). The Q* point from the summary receiver operating curve where the sensitivity and specificity were equal was 0.82 (95% CI: 0.78, 0.85) for radiography, 0.80 (95% CI: 0.76, 0.83) for ultrasound, and 0.75 (95% CI: 0.58, 0.86) for clinical examination. Only one study used computed tomography as the reference standard. This was a general practice study using clinical examination with a sensitivity of 0.85 (95% CI: 0.82, 0.89), specificity of 0.23 (95% CI: 0.18, 0.27), positive LR of 1.10, and negative LR of 0.64.
Comment: The quality of evidence is downgraded by inconsistency (variability in results).
Clinical comment: If a correct diagnosis is important, i.e. if antibiotic treatment is considered, ultrasound or radiography should be used as diagnostic aids.