Table 1.

The Baseline Characteristics of the Studies

Study	Study design	Country	Latitude	Disease	No. of Patients	No. of Deficiency	No. of Normal	Vitamin D Deficiency Definition (ng/mL)	QS
Olmedo et al.29	CS	Magala, Spain	36.72	CD+UC	224	65	159	<20	9
Domislovic et al.19	CS	Zagreb, Croatia	45.82	CD+UC	83	59	24	<20	8
Law et al.27	CS	Chandigargh, India	30.73	UC	80	46	34	<20	9
Pallav et al.30	CS	Jackson, USA	30.83	CD+UC	211	73	138	<20	7
Castro et al.17	CS	Guimarães, Portugal	41.43	CD+UC	76	23	53	<20	8
Mentella et al.28	CS	Chicago, USA	41.87	CD+UC	206	65	141	<20	7
Basson et al.13	CS	Cape Town	33.92	CD	185	106	79	<30	9
Blanck et al.15	CS	Philadelphia, USA	39.95	UC	34	19	15	<30	9
Bhagavathula et al.14	PC	Atlanta, GA, USA	33.75	CD+UC	148	80	68	<20	5
Tran et al.37	PC	Cleveland, USA	41.47	CD+UC	112	76	36	<30	7
Bours et al.16	PC	Amersfoort, Netherlands	52.92	CD+UC	281	160	121	<20	9
Frigstad et al.20	PC	Norway	59.28	CD+UC	408	213	195	<20	7
Kabbani et al.25	PC	Pittsburgh, USA	40.43	CD+UC	965	291	674	<30	8
Scotti et al.31	RC	Rome, Italy	41.9	CD+UC	300	186	114	<20	6
Torella et al.32	RC	Buenos Aires, Argentina	34.33	CD+UC	59	39	20	<30	9
Janssen et al.23	RC	Freiburg, Germany	53.85	CD+UC	384	232	152	<20	8
Bruyn et al.24	RC	Amsterdam, Netherlands	52.37	CD	101	55	46	<20	8
Ulitsky et al.33	RC	Milwaukee, USA	43.03	CD+UC	504	241	263	<20	6
Chatu et al.18	RC	London, UK	51.5	CD+UC	168	113	55	<20	7
Fu et al.21	RC	Vancouver, Canada	49.23	CD+UC	100	39	61	<20	5
Kyong et al.26	RC	Seoul, Korea	37.55	CD+UC	87	64	23	<20	8
Zullow et al.35	RC	Baltimore, USA	39.23	CD+UC	255	99	156	<20	6
Hausmann et al.22	RC	Frankfurt, Germany	50.03	CD+UC	470	281	188	<30	7
Juneja et al.36	RC	Washington, USA	38.88	CD+UC	156	122	34	<30	5
Zator et al.34	RC	Boston, USA	52.98	CD+UC	101	59	42	<30	6

CS, cross-sectional; PC, prospective cohort; RC, retrospective cohort; QS, quality score.