Table 4.

Subgroup analyses to explore the reasons for heterogeneity in observational studies

Variable25(OH)D LevelPTH Level
MD (95% CI); n Trials or ComparisonsPMD (95% CI); n Trials or ComparisonsP
Baseline vitamin D level
    <10 ng/ml34.23 (20.19 to 47.55); 30.008−46.93 (−102.71 to 8.84); 30.81
    10 to 20 ng/ml25.43 (18.98 to 31.89); 12−46.12 (−66.28 to −25.96); 12
    20 to 30 ng/ml14.98 (9.20 to 20.75); 3−35.07 (−63.63 to −6.51); 2
Baseline PTH level
    <100 pg/ml29.00 (24.61 to 33.38); 10.14−13.00 (−65.70 to −39.70); 10.17
    101 to 200 pg/ml32.32 (23.07 to 41.57); 7−33.37 (−49.73 to −17.01); 7
    >200 pg/ml21.27 (14.65 to 27.89); 9−56.97 (−81.45 to −32.49); 9
Study duration
    <3 months32.05 (21.60 to 42.49); 70.22−47.49 (−70.46 to −24.52); 70.90
    3 to 6 months22.29 (13.19 to 31.40); 5−38.49 (−72.92 to −4.07); 4
    >6 months21.94 (16.63 to 27.26); 6−42.06 (−71.91 to −12.21); 6
Vitamin D dose
    KDOQI recommended18.57 (13.24 to 23.90); 40.04−31.07 (−51.13 to −11.00); 40.19
    others26.99 (20.89 to 33.09); 14−50.50 (−71.87 to −29.12); 13
Number of study participants
    <5027.11 (18.08 to 36.13); 90.31−31.76 (−47.41 to −16.12); 80.09
    50 to 10021.04 (14.85 to 27.23); 5−69.71 (−110.76 to −38.67); 7
    >10027.67 (20.67 to 34.67); 4−32.05 (−62.17 to −1.92); 2