The quality of evidence is downgraded by imprecise results (small studies with few patients), heterogeneity in interventions and outcomes, study quality (unclear allocation concealment and blinding) and indirectness (differences between the population of interest and those studied).
A Cochrane review «Saline nasal irrigation for acute upper respiratory tract infections»1 «King D, Mitchell B, Williams CP et al. Saline nasa...»1 included 5 studies that randomised 544 children (three studies) and 205 adults (exclusively from two studies). One study included 143 adults with the diagnosis of acute rhinosinusitis or common cold, one study included 69 children with the diagnosis of acute sinusitis, and in the rest the diagnosis was URTI, common cold or influenza. They all compared saline irrigation to routine care or other nose sprays, rather than placebo.
Most outcome measures differed greatly between included studies and therefore could not be pooled. Most results showed no difference between nasal saline treatment and control. However, one larger trial, conducted with children, did show a significant reduction in nasal secretion score (mean difference (MD) -0.31, 95% CI -0.48 to -0.14) and nasal breathing (obstruction) score (MD -0.33, 95% CI -0.47 to -0.19) in the saline group. However, a MD of -0.33 on a four-point symptom scale may have minimal clinical significance. The trial also showed a significant reduction in the use of decongestant medication by the saline group. Minor nasal discomfort and/or irritation was the only side effect reported by a minority of participants.
| Outcome | Participants (Studies) | Assumed risk – Standard treatment alone | Corresponding risk – Normal saline plus standard treatment | Relative effect (95% CI) |
|---|---|---|---|---|
| Mean days to wellness (patient reports) | 111 (2) | The mean days to wellness in the control groups was 9.24 days | The mean days to wellness in the intervention groups was 0.74 lower (2.58 lower to 1.11 higher) | |
| Antibiotic usage (patient reports) | 422 (2) | 89/1000 | 60/1000 | OR 0.65 (0.29 to 1.46) |
| Sore throat (patient reported symptom scale from 1 to 4) | 390 (1) | The mean sore throat in the control groups was 1.23 points | The mean sore throat in the intervention groups was 0.14 lower (0.24 to 0.04 lower) |