Table 1.

Characteristics of studies included in the meta-analysis.

Study (year)	Sample size	Ethnicity	Study design	NOS score	Disease	Sulfasalazine dose	Genotyping method	SNPs for genotyping
Sabbagh et al.24	11	Mixed	Prospective cohort study	6	CDLE	0.5–2 g/day	PCR-RFLP or allele-specific PCR	rs1208 rs1041983 rs1799929 rs1799930 rs1799931 rs1801279 rs1801280
Ricart et al.25	64	Caucasian	Retrospective cohort study	6	UC	1–4 g/day	DNA microarray or DNA sequencing	rs1208 rs1041983 rs1799929 rs1799930 rs1799931 rs1801279 rs1801280
Tanaka et al.26	144	Japanese	Retrospective cohort study	6	RA	0.5–1.5 g/day	PCR-RFLP or allele-specific PCR	rs1208 rs1041983 rs1799929 rs1799930 rs1799931 rs1801279 rs1801280
Tanigawara et al.27	13	Japanese	Retrospective cohort study	4	IBD	0.5–6 g/day	PCR-RFLP	rs1799929 rs1799930 rs1799931
Kumagai et al.28	96	Japanese	Retrospective cohort study	5	RA	0.5–1 g/day	PCR-RFLP	rs1799929 rs1799930 rs1799931
Chen et al.29	68	Han Chinese	Prospective cohort study	6	IBD	NA	PCR-RFLP	rs1799929 rs1799930 rs1799931
Taniguchi et al.30	186	Japanese	Retrospective cohort study	4	RA	0.5–1.5 g/day	TaqMan	rs1041983 rs1799929 rs1799930 rs1799931
Hou et al.31	266	Han Chinese	Prospective cohort study	8	AS	1.5–3 g/day	PCR-RFLP	rs1799929 rs1799930 rs1799931
Wiese et al.32	229	Mixed	Prospective cohort study	8	RA	0.5–3 g/day	TaqMan	rs1041983 rs1801280

AS: ankylosing spondylitis; CDLE: chronic discoid lupus erythematosus; IBD: inflammatory bowel disease; NA: not available; NOS: Newcastle‐Ottawa Scale; PCR: polymerase chain reaction; RA: rheumatoid arthritis; RFLP: restriction fragment length polymorphism; SNP: single nucleotide polymorphism; UC: ulcerative colitis.