Table 4.
Subgroup analyses to explore the reasons for heterogeneity in observational studies
| Variable | 25(OH)D Level |
PTH Level |
||
|---|---|---|---|---|
| MD (95% CI); n Trials or Comparisons | P | MD (95% CI); n Trials or Comparisons | P | |
| Baseline vitamin D level | ||||
| <10 ng/ml | 34.23 (20.19 to 47.55); 3 | 0.008 | −46.93 (−102.71 to 8.84); 3 | 0.81 |
| 10 to 20 ng/ml | 25.43 (18.98 to 31.89); 12 | −46.12 (−66.28 to −25.96); 12 | ||
| 20 to 30 ng/ml | 14.98 (9.20 to 20.75); 3 | −35.07 (−63.63 to −6.51); 2 | ||
| Baseline PTH level | ||||
| <100 pg/ml | 29.00 (24.61 to 33.38); 1 | 0.14 | −13.00 (−65.70 to −39.70); 1 | 0.17 |
| 101 to 200 pg/ml | 32.32 (23.07 to 41.57); 7 | −33.37 (−49.73 to −17.01); 7 | ||
| >200 pg/ml | 21.27 (14.65 to 27.89); 9 | −56.97 (−81.45 to −32.49); 9 | ||
| Study duration | ||||
| <3 months | 32.05 (21.60 to 42.49); 7 | 0.22 | −47.49 (−70.46 to −24.52); 7 | 0.90 |
| 3 to 6 months | 22.29 (13.19 to 31.40); 5 | −38.49 (−72.92 to −4.07); 4 | ||
| >6 months | 21.94 (16.63 to 27.26); 6 | −42.06 (−71.91 to −12.21); 6 | ||
| Vitamin D dose | ||||
| KDOQI recommended | 18.57 (13.24 to 23.90); 4 | 0.04 | −31.07 (−51.13 to −11.00); 4 | 0.19 |
| others | 26.99 (20.89 to 33.09); 14 | −50.50 (−71.87 to −29.12); 13 | ||
| Number of study participants | ||||
| <50 | 27.11 (18.08 to 36.13); 9 | 0.31 | −31.76 (−47.41 to −16.12); 8 | 0.09 |
| 50 to 100 | 21.04 (14.85 to 27.23); 5 | −69.71 (−110.76 to −38.67); 7 | ||
| >100 | 27.67 (20.67 to 34.67); 4 | −32.05 (−62.17 to −1.92); 2 | ||