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Running title: Meta-analysis of HIV prevalence among LDTDs
1. This is the first meta-analysis of HIV prevalence among LDTDs in various countries.
2. Sixteen eligible studies with 1 014 HIV infections among 13 107 LDTDs were included.
3. The prevalence of HIV among LDTDs declined in recent years.
4. African LDTDs showed a higher prevalence of HIV than Asian LDTDs.
5. A high HIV prevalence among the LDTDs was considered.
Objective: To assess the prevalence of HIV among long-distance truck drivers (LDTDs).
Methods: We searched Medline and Embase databases through August, 2014 for selecting relevant studies. Heterogeneity was assessed by using the Cochran Q statistic and I2 test. Meta-analyses were done with the random effects model combining the prevalence of HIV among LDTDs and corresponding 95% confidence interval (CI). Subgroup analyses were performed based on sample size, study location and publish year of studies. Egger’s test was used to detect publication bias.
Results: A total of 16 eligible studies with 1 014 HIV infections among 13 107 LDTDs were included in this meta-analysis. Overall prevalence of LDTDs of 4.52% (95% CI: 1.04%-9.96%) with significant heterogeneity (Q = 1939.53, P < 0.05, I2 = 99.2%) was calculated using the random effect model. Subgroup analysis showed no significant differences between subgroups of sample size. However, HIV prevalence in African LDTDs and studies published between 1989 and 2005 were significantly higher than the other two subgroups. Egger’s test showed that no publication bias was observed (t = 0.1698, P = 0.8676).
Keywords: HIV prevalence; Long-distance truck drivers; Meta-analysis
Human Immunodeficiency Virus (HIV), a lentivirus (a member of retrovirus) results in the acquired immunodeficiency syndrome (AIDS) . It is one of the most serious health and socioeconomic problems faced by the world today. According to an investigation by the World Health Organization (WHO), 35 million people were living with HIV at the end of 2013. Infection of HIV occurs by the transfer of bodily fluids, including blood, vaginal fluid, semen, breast milk or pre-ejaculate. HIV virus can destroy the human immune system through a number of mechanisms and cause death .
Long-distance truck drivers (LDTDs) play a major role in the spread of HIV/AIDS in many countries and lots of situations related with LDTDs might contribute to the transmission of HIV [3-5]. Two recent studies in South Africa and Azerbaijan found HIV prevalence of 27.8 and 14.5% respectively among LDTDs [6, 7]. LDTDs are easily hurt by sexually transmitted diseases for several reasons, LDTDs are always on the road, may keep away from their regular partners for long, less social constraints, be inclined to select commercial sex partners, and subject to high-risk sexual networks [8-10]. LDTDs may have little or no access to sexual health services and commodities, including timely and effective cure of sexually transmitted infections (STIs), condoms, and other prevention interventions [11, 12].
Numerous studies reported the prevalence of HIV among LDTDs in many countries. However, the HIV prevalence was inconsistent and fluctuated in a wide range. Moreover, the previous meta-analysis  just summarized the prevalence of HIV among LDTDs in China. Thus, a global meta-analysis is needed to systematically review the studies. In this study, we systematically reviewed and meta-analyzed the English studies published in various countries to determine the prevalence of HIV in LDTDs. The result may provide a basis and more effective information for developing and expanding HIV prevention and treatment interventions for LDTDs.
Materials and methods
We systematically searched Pubmed, Medline and Embase databases through August, 2014 to select relevant studies which identified the HIV prevalence of LDTDs. The search terms were “long-distance truck drivers” or “LDTDs” or “truck drivers” or “truckers” and “HIV” or “human immunodeficiency virus” or “AIDS” or “acquired immune deficiency syndrome”.
Studies met the following criteria were included: 1) the participants were LDTDs; 2) prevalence of HIV among LDTDs was measured; 3) HIV testing methods were described clearly.
The following studies were excluded: 1) studies published on a language other than English; 2) data of the studies were incomplete or unavailable; 3) studies were reviews, letters and comments. For duplicates or some studies containing the common population, only the most recent or complete one was included.
Screening and data extraction
All of studies were screened independently by two reviewers using the inclusion and exclusion criteria. Subsequently, data were extracted by two reviewers independently using a standardised data extraction form. Details about studies (study design, name of the first author, year of study and publication and study location) and participants (age, the test methods of HIV, sample size and number of HIV infections) were extracted. The two reviewers exchanged their forms after the data extraction and discrepancies were resolved by discussion.
Heterogeneity was assessed using the Cochran Q statistic and I2 test . P < 0.05 and I2 > 50% represent a significant heterogeneity. The prevalence of HIV obtained by Freeman-Tukey double arcsine transformation (FDF) method  and their corresponding 95% confidence interval (CI) were combined using a random effects model. Subgroup analyses were performed based on study location and sample size. We compared the prevalence between subgroups using a two sided z test. Egger’s test  was used to detect publication bias. All of statistical analyses were performed using R 3.10 software (R Foundation for Statistical Computing, Beijing1, China, Package: Meta).
The selection process of included studies was shown in Fig. 1. A total of 509 studies were identified by initial search. First, 292 studies were excluded by reviewing title and abstract. Then, 150 duplicates and 51 studies with unavailable data were excluded. Finally, 16 eligible studies [6, 7, 17-30] were included in this meta-analysis.
Characteristics of the included studies
As shown in Table 1, a total of 16 eligible studies, including 1 014 HIV infections among 13 107 LDTDs were considered in this meta-analysis. These studies published from 1989 to 2014, including 15 cross-sectional articles and 1 surveillance report. The range of prevalence of HIV was 0-26.49%. Most of the included studies concentrated in developing countries of Asia and Africa. The method of HIV detection included ELISA (enzymelinked immunosobent assay), EIA (Enzyme immunoassay), and etc.
As shown in Fig. 2, overall prevalence of LDTDs of 4.52% (95% CI: 1.04%-9.96%) with significant heterogeneity (Q = 1939.53, P < 0.05, I2 = 99.2%) was calculated using the random effects model.
The results of subgroup analyses were shown in Table 2. Based on sample size, the difference of HIV prevalence among LDTDs between subgroups was not significant (P = 0.61). However, HIV prevalence among LDTDs showed notable variation by region. The HIV prevalence in Africa was significantly higher than in Asia(P < 0.01). As well, HIV prevalence in studies published between 1989 and 2005 was significantly higher (P < 0.01) than in studies published between 2006 and 2014.
Egger’s test showed that no publication bias was observed (t = 0.1698, P = 0.8676).
In this study, we systematically reviewed and meta-analyzed the results of studies reporting HIV prevalence of LDTDs. The overall HIV prevalence of LDTDs was 4.52% (95% CI: 1.04%-9.96%). Subgroup analyses showed that the HIV prevalence among LDTDs declined in recent years. Moreover, the HIV prevalence in African LDTDs was significantly higher than in Asian LDTDs.
HIV prevalence of LDTDs is significantly higher than the total HIV prevalence of 0.8% in adults aged 15-49 years worldwide which is from a statistical data of WHO in 2012. This result shows that LDTDs is a high-risk group of HIV infection. This may be due to their risky sexual behaviors, including have more than one sexual partner, low condom use and injecting narcotics while on the road.
Our result showed that the HIV prevalence of LDTDs in Africa was significantly higher than in Asia. This result is consistent with the low HIV prevalence (0.19%, 95% CI: 0.15-0.24%) among Chinese LDTDs in the previous meta-analysis . We suggest that the reasons may be the differences in the culture, education and region among LDTDs.
A comforting consequence in this study showed that the prevalence of HIV among LDTDs declined in recent years. This result reflects that HIV infection among LDTDs has been given much attention and some achievements were obtained in prevention interventions. In addition, with more developed science and technology and more convenient traffic. The previous main long-distance transportation routes are replaced by national expressway that results in a reduction of the period on road of truck drivers.
Several strengths of this meta-analysis should be noted. Firstly, this is the first systematical analysis for evaluating the prevalence of HIV among LDTDs in various countries or regions. Secondly, no publication bias was observed. Thirdly, the methods for detecting HIV in original researches were rigorous. There are also some limitations in this meta-analysis. Firstly, most of included studies are cross-sectional studies. Thus, absent of control groups may cause some selection bias. Moreover, we can’t obtain the morbidity of HIV among LDTDs from cross-sectional surveys. Secondly, because of the incomplete information in some included studies, we can’t adjust some confounders (age, gender period spent on road and income level) which may affect our result.
Heterogeneity is also a limitation in this meta-analysis. We conducted subgroup analyses to find the source of heterogeneity. After grouping, the heterogeneity declined, but remained significant. We suggest that the main source of heterogeneity is discrepancy of region. Sometimes, different regions in one country showed a significant difference. For example, the prevalence of HIV infection among LDTDs varied from as low as 0-0.16 among Brazilian and American LDTDs [22, 30] to as high as 26-26.49% among African LDTDs [7, 19]. Although we had adjusted some factors, including sample size, location of study and publication year, the residual confounding factors such as living habit and environment, culture, gender and age would affect our result.
In conclusion, the high HIV prevalence among the LDTDs suggests that LDTDs is a high-risk group of HIV infection. Therefore, health education, prevention interventions and HIV care services in this population are needed, especially located in South and East Africa.