. 2013 Sep 4;8(9):e73055. doi: 10.1371/journal.pone.0073055

Table 2. Assessment of bias: measures of the studies included in the analysis.

Measure	Variables	N-studies
BV outcome measure	prevalence	43^a
(55 studies, 57 outcomes)	incidence	10^a
	recurrence	4^a
Hormonal contraceptive type	Combined HC-use	33^a
(55 studies, 66 associations)	POC HC-use	13^a
	Unspecified HC-use	20^a
BV diagnostic method	Nugent	30^a
(n = 55 studies)	Amsel (modified Amsel n = 3)	21^a
	Amsel & Nugent	1^a
	Other: Spiegel (n = 1), Ison-Hay (n = 1)	2^a
Setting/recruitment venue	Sexual or reproductive health service (SRHS)	37^b
(n = 55 studies)	General community healthcare service (GCHS)	7^c
	Sex worker service (SWS)	8^d
	Population based (POP)	2^e
HC-use comparison group	no contraceptive use	8^a
(n = 66 associations)	all non-hormonal contraceptives or none	23^a
	all non-combined contraceptives or none	27^a
	all non-progesterone contraceptives or none	8^a

references for first three summary measures provided in Table 1; references for the last two summary measures footnoted here:

[10], [12], [14], [15], [17], [24]–[27], [29], [45]–[54], [57], [58], [60], [75], [77]–[88],

[7], [13], [16], [42]–[44], [59],

[18], [35]–[41].

[30], [55].

Key: HC = hormonal contraception, combined = combined oestrogen- and progesterone-containing methods of HC, POC = progesterone only containing methods of HC.