Table 1.

The characteristics of included studies for assessing vitamin D level.

References	Country	Study design	Latitude	HIV age (year)	Control age (year)	Male percentage	BMI	Sample size	HIV number	Control number	VD level in HIV	VD level in control	P-value
Ross et al. (29)	USA	Cross-sectional study	41°30′N	49	38	80.9	26.19	183	149	34	25.84 (0.432)	20.84 (0.416)	<0.001
Atteritano et al. (34)	Italy	Case-control study	38°13′N	45.36	44.85	16	24.9	200	100	100	20.29 (4.05)	35.77 (6.5)	<0.001
Thuppal et al. (30)	USA	Cross-sectional study	multicenter	37.7	34.3	50	28.3	15792	85	15707	21.793 (13.74)	25.461 (28.36)	0.233
Zhang et al. (36)	China	Cohort study	39°55′N	37.3	37.19	87.5	22.88	80	40	40	15.93 (6.49)	19.12 (9)	0.069
Zhang et al. (33)	USA	Cohort study	multicenter	NA	NA	100	NA	658	466	192	18.5 (8.889)	18 (6.593)	0.482
Adeyemi et al. (18)	USA	Cross-sectional study	multicenter	44	41	0	28.57	1778	1268	510	16 (11.111)	14 (8.148)	<0.001
Ceballos et al. (37)	Chile	Cross-sectional study	33°26′S	31.2	33.3	100	24.44	91	70	21	17.7 (6.64)	20.8 (7)	0.064
Currò et al. (35)	Italy	Case-control study	38°13′N	43.2	41.5	59.8	NA	97	57	40	23.96 (10.871)	34.96 (12.396)	<0.001
Hileman et al. (31)	USA	Cohort study	41°30′N	40	37	69.3	26.65	88	47	41	13.245 (8.258)	15.1 (6.81)	0.255
Janbakhsh et al. (28)	Iran	Case-control study	34°19′N	40.11	45.59	87.2	NA	196	98	98	29.56 (27.27)	30.63 (18.66)	0.749
Klassen et al. (38)	Australia	Cross-sectional study	37°49′S	41	50	56	NA	4650	997	3653	24.8 (11.852)	27.6 (9.185)	<0.001
Mikula et al. (39)	Poland	Cross-sectional study	52°15′N	44.9	56.6	73.9	NA	188	148	40	29.68 (14.36)	30 (11.04)	0.896
Flauzino et al. (40)	Brazil	Cross-sectional study	23°30′S	40	40	53.5	25.17	441	314	127	29.94 (11.695)	29.07 (9.128)	0.453
Paul et al. (41)	India	Cross-sectional study	12°55′N	38.45	38.6	100	23.13	105	70	35	19.7 (8.804)	22.2 (5.6)	0.126

NA, not available; N: north; S: south; P-value: for evaluating the difference in VD levels between HIV and control groups.