Summary of findings 3. Light therapy compared with no light therapy for prevention of SAD.
| Light therapy (bright white or infrared) compared with no light therapy for prevention of SAD | ||||||
| Patient or population: all participants were known SAD patients who had been successfully treated with conventional light therapy in previous winters Settings: outpatient field study; participants chose when (between 6 am and 9 am) and where they would use the visors Intervention: light therapy Comparison: no light therapy | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect (95% CI) | Number of participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| No light therapy | Infrared light therapy | |||||
| Incidence of SAD (SIGH‐SAD score ≥ 20) (follow‐up 26 weeks) |
Low | RR 0.57 (0.30 to 1.10) | 38 (1 RCT) | ⊕⊝⊝⊝ Very lowa,b | ||
| 300 per 1000 | 171per 1000 (90 to 330) |
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| Moderate | ||||||
| 500 per 1000 | 285 per 1000 (150 to 550) |
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| High | ||||||
| 600 per 1000 | 342 per 1000 (180 to 660) |
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| Incidence of severe SAD (SIGH‐SAD‐SR (≥ 40)) (follow‐up 26 weeks) |
Study population | RR 0.21 (0.04 to 1.05) | 38 (1 RCT) | ⊕⊝⊝⊝ Very lowa,b | ||
| 333 per 1000 | 70 per 1000 (13 to 350) | |||||
| Overall discontinuation (follow‐up 26 weeks) |
Study population | RR 1.94 (0.27 to 14.01) | 46 (1 RCT) | ⊕⊝⊝⊝ Very lowa,b | ||
| 100 per 1000 | 194 per 1000 (27 to 1000) | |||||
| *The basis for the assumed risk (e.g. median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI) CI: confidence interval; RCT: randomised controlled trial; RR: risk ratio; SIGH‐SAD‐SR: Structured Interview Guide for the Hamilton Depression Rating Scale‐Seasonal Affective Disorders self‐rating version | ||||||
| GRADE Working Group grades of evidence High quality: further research is very unlikely to change our confidence in the estimate of effect Moderate quality: further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate Low quality: further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate Very low quality: we are very uncertain about the estimate | ||||||
aDowngraded two levels because of severe risk of bias due to non‐blinding and unclear randomisation process and allocation concealment; no intention‐to‐treat analysis was reported, outcomes were self‐rated, compliance throughout study duration was not checked and participant characteristics were not reported comprehensively. bDowngraded one level because of small sample size (lack of power and random error could have influenced results).