Table 2.

General characteristics of the included studies.

Study reference	Country	Criteria of constipation	N	DRE	Comparative test	Extracted data
Soh et al. (2015)	Korea	NA	253	2 of as-pc/as-nr, pe-i, pd-a	HRAM (type I–IV DD)	tp = 193, fp = 19, fn = 14, tn = 27
Tantiphlachiva et al. (2010)	America	Rome III criteria	209	2 of as-pc/as-nr, am-nc, pd-a	AM	sensitivity = 75%, specificity = 87%, PPV = 97%, and NPV = 37%
Karlbom et al. (1998)	Sweden	NA	106	pr-pc	AM + CTT	tp = 19, fp = 12, fn = 14, tn = 91
Guo et al. (2004)	China	Rome II criteria	118	pr-pc	DEF + EMG	sensitivity = 82.53%, specificity = 85.21%,
						False positive rate = 14.82%,
						False negative rate = 17.52%
Jain et al. (2018)	India	NA	60	as-pc, as-nr, am-nc, pd-a	AM	tp = 23, fp = 5, fn = 10, tn = 22

DRE: digital rectal examination; HRAM: high-resolution anorectal manometry; AM: anorectal manometry; DEF: defecography; EMG: electromyography; CCT: colonic transit time; as-pc: anal sphincter paradoxical contraction; as-nr: anal sphincter nonrelaxing; am-nc: abdominal muscles not contracted; pd-a: perineal descent absent; pe-i: push effort impaired; pr-pc: puborectalis paradoxical contraction; PPV: positive predictive value; NPV: negative predictive value; tp: true positive; fp: false positive; fn: false negative; tn: true negative; NA: not available.