Betel quid chewing and oral potential malignant disorders and the impact of smoking and drinking: A meta-analysis

Table 1 Search strategy

Number	Contents
1	Oral potentially malignant disorders OR oral precancerous lesions OR oral premalignant lesions OR oral leukoplakia OR oral submucous fibrosis OR oral lichen planus OR oral erythema OR erythroplakia
2	Betel quid OR betel nut OR areca nut OR pan chewing
3	Alcohol OR drinking OR alcoholic beverage OR ethanol
4	Tobacco OR smoking OR cigarettes
5	(#1) AND (#2) AND (#3)
6	(#1) AND (#2) AND (#4)
7	(#5) OR (#6)

Table 2 Selected studies characteristics

Ref.	Publication year	Study diseases	Study area	Study design	Sample size	Age	ORs and 95% confidence intervals					NOS/AHRQ scale
							BQ	SM	DK	BQ + SM	BQ + DK
Yang et al[12]	2001	Leukoplakia, OSF	Taiwan	Cross sectional	312	20 and above	4.51 (1.30-15.62)	1.05 (0.5-2.23)	1.8 (0.88-3.73)	3.75 (0.99-14.19)	7.49 (1.95-28.69)	8
Lee et al[13]	2003	Leukoplakia	Taiwan	1:4 case control	125:876	15 and above	22.3 (11.3-43.8)	6.1 (3.4-10.6)	1.8 (1.1-2.8)	40.2 (16.3-99.2)	16.8 (7.2-39.5)	8
		OSF		1:4 case control	94:876	15 and above	40.7 (16-103.7)	7 (3.5-14.3)	1.8 (1.1-3.1)	57.9 (16-209.6)	31.7 (10.1-99.3)
Yang et al[26]	2005	OSF	Taiwan	1:1 case control	62:62	20 and above	4.51 (1.20-16.94)	——	——	8.68 (1.87-40.23)	——	7
Chung et al[25]	2005	Leukoplakia	Taiwan	Cross sectional	525	15 and above	——	3.69 (1.61-8.43)	2.36 (0.91-6.13)	8.54 (2.58-28.23)	5.82 (1.10-30.84)	7
Thomas et al[7]	2008	Leukoplakia	PNG	Case control	197:1282	18 and above	3.8 (1.7-8.4)	6.4 (4.1-9.9)	——	24.3 (8.7-67.4)	——	6
Mehrotra et al[27]	2013	OSF	India	Case control	448:2688	15 and above	6.38 (4.29-9.48)	4.31 (2.84-6.55)	3.19 (1.36-7.45)	——	9.79 (6.51-14.75)	8
Chher et al[23]	2018	OPMDs	Cambodia	Cross sectional	1614	18 and above	6.75 (3.32-13.72)	3.74 (1.89-7.41)	1.88 (0.81-4.36)	——	5.40 (0.64-45.36)	7
Ikeda et al[24]	1995	OSF, lichen planus	Cambodia	Cross sectional	1319	15 and above	21.66 (5.06-92.75)	8.89 (1.78-44.42)	——	17.16 (3.09-95.48)	——	7
Ray et al[21]	2013	Leukoplakia, OSF	India	Case control	698:766	10 and above	5.15 (2.63-10.09)	4.38 (2.14-8.96)	——	5.75 (2.32-14.27)	——	7

ORs: odds ratios; OSF: Oral submucous fibrosis; OPMDs: Oral potential malignant disorders; BQ: Betel quid chewing; SM: Smoking; DK: Alcohol drinking; BQ + SM: Betel quid chewing and smoking; BQ + DK: Betel quid chewing and alcohol drinking; NOS: Newcastle-Ottawa Scale; AHRQ: The Agency for Healthcare Research and Quality.

Table 3 Pooled odds ratios and 95% confidence intervals in all exposure categories

Exposure category	Pooled OR	95%CI
BQ	8.70	5.18-14.61
SM	4.35	3.06-6.20
DK	1.95	1.50-2.55
BQ and SM	14.38	7.14-28.95
BQ and DK	11.12	8.00-15.45

OR: Odds ratio; BQ: Betel quid chewing; SM: Smoking; DK: Alcohol drinking; CI: Confidence interval.