At the initial search strategy, 1123 articles were found. First, the duplicates were removed, and then 663 articles were entered into the screening stage according to the title. At this step, 430 articles were removed, and 233 papers were evaluated based on their abstracts. Then, 50 articles remained and entered into the screening phase based on their full texts. Of these articles, 27 were excluded due to the non-related outcomes to the present study, 11 cases because of different statistical populations, and 2 cases owing to lack of full-text availability. Finally, ten studies (2, 16-24) were entered into the analysis. Out of these articles, eight studies (2, 16-20, 22, 24) reported the prevalence of HBV, and eight studies (2, 16-18, 20, 21, 23, 24) reported HCV prevalence in transgender and LGBT people. (Figure 1).
Table 1 lists the general characteristics of the included studies. Of all studies, two (16, 17) had been conducted in the LGBT community (Total sample size = 2150), and eight (2, 18-24) in the transgender community (Total sample size = 4273). Seven studies were conducted with cross-sectional design in Argentina (2), The Republic of Dominican (16), Spain (17), the United States (22), Nigeria (23), and Indonesia (24), in contrast, three ones had been retrospectively conducted in Pakistan (19), Italy (18), and the United States (21).
Table 1
Baseline characteristics of the included studies.
Authors
(Year)
|
Type of study
(Country)
|
Study population
(Type)
|
Age
(Mean)
|
Sample size
(N)
|
HBV Prevalence
N (%)
|
HCV Prevalence
N (%)
|
Number
(Type of laboratory test)
|
Johnston L, et al. (2013) (16)
|
Cross-sectional
(Dominican Republic)
|
LGBT
|
≥15
|
1388
|
28 (2.05%)
|
53 (3.85%)
|
HBV: HBsAg BIO-CARD HCV: Bioblot HCV
|
Gutierrez M, et al. (2004) (17)
|
Cross-sectional
(Spain)
|
LGBT
|
18-41
|
762
|
27(3.5%)
|
6(0.8%)
|
HBV: Microparticle Enzyme Immunoassay
HCV: ELISA, line immunoassay
|
Carobene M, et al. (2013) (2)
|
Cross-sectional
(Argentina)
|
TGs [Both]
|
29
|
273
|
106 (40%)
|
12(4.5%)
|
ELISA, particle
Agglutination
|
Luzzati R, et al. (2014) (18)
|
Retrospective
(Italy)
|
TGs [Both]
|
33.5±7.7
|
243
(MTF:
218
FTM:
25)
|
MTF:
10 (4.6 %)
FTM:
2 (4 %)
|
MTF:
8 (3.5 %)
FTM:
2 (8 %)
|
HBV: immunoassays Enzygnost, Chemiluminescent
Microparticle Immunoassay, CMIA
HCV: immunoassay Ortho HCV 3.0 Elisa Test System, immunoblotting
Chiron Riba HCV 3.0 SIA
|
Ahsan A, et al. (2017) (19)
|
Retrospective
(Pakistan)
|
TGs [Both]
|
All ages
|
877
|
NR
|
128 (14.6%)
|
HCV: RAPID ICT test, ELISA
|
Brito MO, et al. (2015) (20)
|
Cross-sectional
(Dominican Republic)
|
MTF
|
≥18
|
100
|
4 (4 %)
|
1 (1 %)
|
HBV: hepatitis B
surface antigen (HBsAg II, COBAS, Roche Diagnostics)
HCV: hepatitis C antibody
(anti-HCV II, COBAS, Roche Diagnostics)
|
Krieger D, et al. (2013) (21)
|
Retrospective
(USA)
|
TGs [Both]
|
35.5-41.3
|
1005
|
48 (4.8%)
|
NR
|
HBV serology
(Surface antigen and antibody)
|
Facente SN, et al. (2021) (22)
|
Cross-sectional
(USA)
|
MTF
|
>30
|
951
|
NR
|
236 (24.8 %)
|
HCV: ELISA
|
Adeyemi OA, et al. (2021) (23)
|
Cross-sectional (Nigeria)
|
MTF
|
25
|
717
|
69 (10 %)
|
NR
|
HBV serology
(Surface antigen and antibody)
|
Hadikusumo AA, et al. (2016) (24)
|
Cross-sectional (Indonesia)
|
TGs [Both]
|
19 – 60
|
107
|
10 (9.3 %)
|
7 (6.5 %)
|
HBV: Reverse passive hemagglutination assay, PCR
HCV: Reverse
particle hemagglutination method, PCR
|
Prevalence of HCV and HBV in LGBT population
Among the included studies, Johnston L et al. (16) and Gutierrez M et al. (17) reported the prevalence of HCV and HBV in the LGBT population, i.e., Lesbian, Gay, Bisexual, Transgender altogether. Johnston et al. (16) estimated the prevalence of HCV as 3.85% and HBV as 2.05% among the LGBT population of the Dominican Republic, and Gutierrez et al. (17) stated the prevalence of HCV and HBV were 0.8% and 3.5% among the LGBT people of Spain, respectively. We did not pool the results of these studies with other included studies since their target population included all lesbians, gays, bisexuals, and transgender people while other included studies investigated only the transgender community. Besides, we will update our study for pooled analysis of these corresponding estimates when further studies have been conducted on the LGBT population.
Prevalence of HCV in the transgender population
The results of 6 studies (2, 18-20, 22, 24) reporting the prevalence of HCV in transgender people were combined and showed that the overall prevalence of HCV in the transgender population around the world was 9% (95%CI: 3-15%) (Figure 2). The heterogeneity percentage of this estimate was 77.16% (p < 0.01). The lowest and highest prevalence among these studies was 1% in Brito MO et al. study (20) and 25% in Facente SN et al. study (22), respectively. Egger's test was used to assess the publication bias, which indicated the presence of publication bias (B: 0.38; SE: 0.09; P: 0.043). In addition, this bias was also confirmed by the funnel plot, and its results were demonstrated in Figure 2. The meta-regression showed that the variables of sample sizes and age of individuals had no significant effect on the cumulative prevalence of HCV in transgender people. Also, the amount of τ2 in the cumulative total prevalence was 0.00. At the same time, this value increased to 0.004 by entering the age and sample sizes variables, showing the lack of age variable effects on transgender people and the sample size of preliminary studies on the prevalence heterogeneity of HCV in the transgender population (Table 2).
Table 2
Meta-regression on the heterogeneity of pooled prevalence.
|
Variables
|
Coefficient
|
Standard Error
|
P-value
|
95 % CI
|
Heterogeneity
|
Lower
|
Upper
|
2 τ
|
HCV in TGs
|
Age
|
-0.122
|
0.043
|
0.655
|
-0.200
|
0.021
|
0.001 / 0.004
|
Sample Size
|
0.002
|
0.001
|
0.412
|
-0.002
|
0.004
|
HBV in TGs
|
Age
|
-0.091
|
0.072
|
0.968
|
-0.117
|
0.078
|
0.055 / 0.001
|
Sample Size
|
0.005
|
0.001
|
0.751
|
-0.004
|
0.007
|
Prevalence of HBV in the transgender population
Six studies (2, 18, 20, 21, 23, 24) reported the prevalence of HBV in transgender people. Luzzati R et al. (18) reported this prevalence in male to female and female to male, separately. Therefore, seven prevalence records of HBV in transgender people were combined and showed that the overall prevalence of HBV in transgender people in the world was 11% (95%CI: 2- 20%). Heterogeneity was 91.43%, which was substantially high (Figure 2). The lowest and highest prevalence was 4% in Brito MO et al. study (20) and 83% in Carobene M et al. study (2) (Figure 2). Also, the publication bias was evaluated using Egger's test and the funnel plot diagram (Figure 3). Egger's test indicated a publication bias (B: 0.55; SE: 0.10; P: 0.019). The results of meta-regression were also expressed in Table 2. Age and sample sizes had no significant effect on the pooled prevalence of HBV in transgender people. Also, the pooled prevalence of τ2 was 0.055. At the same time, by entering the age and sample size variables, this value increased to 0.001, indicating that the age variables of transgender people and the sample size of preliminary studies did not affect HBV prevalence heterogeneity in transgender people (Table 2).
Cumulative Meta-analysis
The cumulative meta-analysis was performed to determine the impact of adding each study on the pooled cumulative prevalence in the order of their publication date. For most HCV in transgender people, the cumulative meta-analysis reported a higher prevalence of HCV in recent studies (20%; 95%CI: 10- 30%) compared to the final incremental majority (9%; 95%CI: 3- 15%; Figure 4a). Meanwhile, the cumulative meta-analysis concerning the prevalence of HBV in transgender people revealed that the recent reports on HBV prevalence in this population (10%; 95%CI: 8- 12%) were almost the same as the final cumulative prevalence (11%; 95%CI: 2- 20%; Figure 4b)
Subgroup Analysis
The results of subgroup analysis based on the type of gender reassignment (male to female or female to male) and continent were shown in Table 3. Three studies (18, 20, 22) reported HCV prevalence in transgender people who had changed gender from male to female. After combining these results, the prevalence of HCV in male to female transgender was estimated as 5% (95%CI: 1-9%). The remarkable point was that the heterogeneity was 55.93%, much lower than the heterogeneity rate of the overall prevalence in Figure 2. Therefore, it could be said that the failure to determine the type of gender change (from male to female and vice versa ) in preliminary studies was a source of heterogeneity in the pooled analysis of the overall prevalence of HCV. Besides, three studies (2, 19, 24) did not specify the type of gender reassignment, and combining these studies demonstrated that the prevalence of HCV in this group was 9% (95%CI: 2-15%); however, due to the lack of separation of transgender based on their gender reassignment, its heterogeneity rate was high (I2 = 90.38%; Table 3). The subgroup analysis based on the continent showed that the pooled prevalence of HCV in the transgender population was 11% (95%CI: 3- 19%) in Asia, 10% (95%CI: 5- 25%) in America, and 4% (95%CI: 1- 6 %) in Europe.
Table 3
Subgroup analysis of the prevalence of HBV and HCV in TGs based on Male to Female, Female to Male, and continents.
Population
|
Subgroup
|
Number of studies
|
Pooled prevalence (95% CI)
|
Between studies
|
Between subgroups
|
I2(%)
|
P heterogeneity
|
Q
|
Q
|
P heterogeneity
|
HCV in TGs
|
Type
|
MTF
|
3
|
5 % (1 – 9 %)
|
55.93 %
|
0.90
|
15.99
|
3.57
|
0.17
|
FTM
|
1
|
8 % (1 – 14 %)
|
-
|
-
|
-
|
Both
|
3
|
9 % (2– 15 %)
|
90.38 %
|
0.00
|
36.68
|
Continent
|
Asia
|
2
|
11 % (3 – 19 %)
|
71.23 %
|
0.06
|
9.09
|
3.41
|
0.18
|
America
|
3
|
10 % (5 – 25 %)
|
76.55 %
|
0.00
|
44.50
|
Europe
|
2
|
4 % (1 – 6 %)
|
0.00 %
|
0.44
|
0.60
|
HBV in TGs
|
Type
|
MTF
|
3
|
6 % (3 – 10 %)
|
79.54 %
|
0.07
|
10.90
|
1.14
|
0.56
|
FTM
|
1
|
8 % (1 – 14 %)
|
-
|
-
|
-
|
Both
|
3
|
18 % (3 – 34 %)
|
88.90 %
|
0.00
|
17.68
|
Continent
|
Asia
|
1
|
9 % (4 – 15 %)
|
-
|
-
|
-
|
8.27
|
0.04
|
America
|
3
|
16 % (8 – 23 %)
|
76.55 %
|
0.00
|
44.8
|
Europe
|
2
|
5 % (2 – 7 %)
|
0.00 %
|
0.44
|
0.37
|
Africa
|
1
|
10 % (7 – 12 %)
|
-
|
-
|
-
|
The subgroup analysis on HBV prevalence based on the type of gender reassignment showed that the prevalence of HBV in male to female transgender was 6% (95%CI: 3- 10%) while after combining the results of studies that had not separated the type of gender reassignment, the prevalence of HBV was 18% (95%CI: 3- 34%). However, the heterogeneity rate in these estimates were high (I2 = 79.54% and I2 = 88.90%, respectively). Besides, This analysis revealed that the pooled prevalence of HBV in transgender people living in America was 16% (95%CI: 8- 23%), and those living in Europe had the pooled HBV prevalence of 5% (95%CI: 2- 7%) (Table 3). It is noteworthy to declare that we could not generalize our findings of subgroup analysis on continents due to a small number of reports in each subgroup; thus, we required more data on each continent for accurate estimation of HCV and HBV prevalence among the transgender population living in each continent.