Table 2. Main characteristics of the selected studies.
| First author, year, and country | Design | Quality | Type of HRD | N | Age range (years) |
Groups |
Follow-up | |
|---|---|---|---|---|---|---|---|---|
| (% women) | Intervention (N) | Control (N) | ||||||
| Berson et al,12 USA | RCT 2x2 factorial | ++ | RP | 601 (38) | 18–49 | Vit A group: Vit A 15 000 IU/d+traces Vit E (146) | Traces Vit A+traces Vit E (149) | 4–6 Years |
| Vit A+E group: Vit A 15 000 IU/d+Vit E 400 IU/d (151) | ||||||||
| Vit E group: Vit E 400 IU/d+traces Vit A (155) | ||||||||
| Berson et al,14 USA | RCT | ++ | RP | 221 (49) | 18–55 | DHA 1200 mg/d+Vit A 15 000 IU/d (105)a | Placebo+Vit A 15 000 IU/d (103)a | 4 Years |
| Hoffman et al,16 USA | RCT | ++ | RP | 44 (0) | 4–38 | DHA 400 mg/d (23) | Placebo group (21) | 4 Years |
| Hoffman et al,9 USA | RCT | + | RP | 78 (0) | 7–31 | DHA 30 mg/kg/d (600-3600 mg/d)+multivitamins complex (41) | Placebo+multivitamins (37) | 4 Years |
| Bahrami et al,11 USA | RCT crossover | + | RP | 45 (38% de 34) | 49.2±9.0b | Lutein 10 mg/d × 12w; 30 mg/d × 12w, placebo × 24w+multivitamins (20) | Placebo × 24w; Lutein 10 mg/d × 12w; 30 mg/d × 12w+multivitamins (25) | 48 Weeks |
| Berson et al,13 USA | RCT | + | RP | 240 (≈51) | 18–60 | Lutein 12 mg/d+Vit A 15 000 IU/d (120) | Placebo+15 000 IU/d Vit A (120) | 4 Years |
| Rotenstreich et al,19 Israel | RCT crossover | ++ | RP | 34 (28) | 21–74 | 9-cis-β-carotene 20 mg/d (16) | Placebo group (18) | 9 Months (3/3/3) |
| Lee et al,18 Canada | RCT crossover | 0 | Best Disease | 8 (0) | 23–64 | DHA 20 mg/kg/d (4) | Placebo group (4) | 8 Months (2/2/4) |
Abbreviations: d; day; DHA, docosahexaenoic acid; HRD, hereditary retinal dystrophy; IU, International Units; RCT, randomised controlled trial; RP, retinitis pigmentosa; Vit, Vitamin; w, weeks;
++, High quality; low risk of bias in the results; +, acceptable quality, some risk of bias in the results; 0, low quality, high risk of bias in the results.
a
N analysed.
b
mean±SD.