Tattooing and the risk of transmission of hepatitis C: a systematic review and meta-analysis
Summary
Objectives
In this systematic literature review we sought to determine whether tattooing is a risk factor for the transmission of hepatitis C.
Methods
A comprehensive search was performed to identify all case-control, cohort or cross sectional studies published prior to November 2008 that evaluated risks related to tattooing or risk factors of transmission of hepatitis C infection.
Results
A total of 124 studies were included in this systematic review, of which 83 were included in the meta-analysis. The pooled odds ratio (OR) and 95% confidence interval (CI) of the association of tattooing and hepatitis C from all studies was 2.74 (2.38–3.15). In a subgroup analysis we found the strongest association between tattooing and risk of hepatitis C for samples derived from non-injection drug users (OR 5.74, 95% CI 1.98–16.66).
Conclusions
Findings from the current meta-analysis indicate that tattooing is associated with a higher risk of hepatitis C infection. Because tattooing is more common among the youth and young adults and hepatitis C is very common in the imprisoned population, prevention programs must focus on youngsters and prisoners to lower the spread of hepatitis infection.
Keywords
- Tattoo;
- Tattooing;
- Hepatitis C;
- Systematic review;
- Meta-analysis
1. Introduction
There has been an increase in the global prevalence of tattooing in recent years. In the USA, 36% of people under 30 have tattoos.1 Studies from Canada indicate that around 8% of high school students have at least one tattoo,2 and 3 and among those who did not have a tattoo, 21% were eager to have one. Tattooing requires injection of pigments into the dermal layer of skin by puncturing the skin 80 to 150 times a second. Since tattoo instruments come into contact with blood and bodily fluids, viral and microbial infections may be transmitted if the instruments are used on more than one person without being sterilized or without proper hygiene techniques. Also, because tattoo dyes are not kept in sterile containers they might play a carrier role in transmitting infections. In light of the increase in the worldwide prevalence of tattoos, it has been postulated that tattooing may play an important role in the transmission of blood-borne diseases such as hepatitis B and hepatitis C.
In the USA, approximately 2.3% of adults aged 20 years or older are positive for anti-hepatitis C virus (HCV) antibody, and between 55% and 84% of these have a chronic infection;4 and 5 however only 5% to 50% of infected adults are aware of their status.6, 7 and 8 It is estimated that 210 000 to 275 000 people are currently infected with hepatitis C in Canada, of whom only 30% are aware of their infection.9
Tattooing among prisoners is another issue of importance. The overall prevalence of hepatitis C among inmates is estimated to be around 25.2% to 37.4%.10, 11, 12, 13 and 14 Close to half of inmates may not know their serostatus, and the rates may vary between men and women.10, 11, 12, 13 and 14 Reusing and sharing tattoo needles is reported to be a common practice among almost 45% of inmates.13 Given that the annual cost of each new case of hepatitis C for the healthcare system is estimated at around US$25 000 to US$30 000,15 the number of new cases of hepatitis that may arise as a result of tattooing has important clinical as well as public health implications. Because the results from epidemiological studies regarding the risk of hepatitis among tattooed individuals are conflicting, we sought to systematically review the literature in order to quantify the risk of hepatitis in tattooed individuals.
2. Methods
2.1. Search strategy
We identified relevant studies and abstracts by searching MEDLINE (1966 to November 2008), EMBASE (1980 to November 2008), Database of Abstracts of Reviews of Effects (DARE; 1991 to November 2008), ACP Journal Club (1991 to November 2008), International Pharmaceutical Abstracts (1970 to November 2008), BIOSIS Previews (1969 to November 2008), Web of Science (1961 to November 2008), and Pubmed. There was no language restriction in selecting the studies. The initial search strategy was developed from the MeSH subject headings ‘hepatitis’ and ‘tattoo’ in MEDLINE. Titles were reviewed for relevance from this search, and subject headings and abstracts were then examined. Appropriate subject headings and keywords were added to the search strategy. The scope notes in MEDLINE and EMBASE were also examined to ensure the correct subject headings were used based on their definitions; other subject headings were included based on previous indexing and the inclusion of keywords based on synonyms used in the scope notes. Consequently, broader MeSH subject headings such as ‘tattooing’, ‘hepatitis’, and ‘hepatitis C’ were included. Proceedings and conference abstracts were searched through the databases PapersFirst (1993) and ProceedingsFirst (1993) up to October 2008. Author names and year of published work from key papers were entered into the cited reference search in the Web of Science. We screened the references of retrieved studies and review articles for any potentially missed articles. In addition, we hand-searched the reference lists of retrieved studies as well as journals related to ‘hepatitis’, ‘hepatology’, ‘blood’, ‘infection’, ‘epidemiology’, and ‘gastroenterology’, and abstracts and books related to hepatitis. We contacted authors to ensure there was no overlap in the sample included in their studies whenever needed.
2.2. Selection criteria
We considered all observational studies that assessed the association between tattooing and hepatitis. Observational studies were included if they (1) clearly defined hepatitis C as either the primary or secondary outcome; (2) clearly defined tattoos as either primary or secondary exposure; (3) presented relative risks or odds ratios and their corresponding confidence intervals or provided enough data to compute these parameters. In the case of a study published in different phases or if data from a study were duplicated in more than one study, we only included the most recent study.
2.3. Data extraction
We created a spreadsheet and recorded study characteristics including author names, publication year, country of study, study design, sample size, study population type, mean age or range, gender of participants, type of risk factors or confounders adjusted for, outcome of interest (hepatitis C), and adjusted odds ratio (OR) and 95% confidence interval (CI). Included articles were reviewed in full by two independent reviewers (SJ and SB). In studies that provided several levels of exposure, each exposure was categorized and analyzed in the designated subgroup. To assess the quality of studies we created a quality assessment scale (0 to 9 points) based on Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines.16 The scale includes reporting the inclusion/exclusion criteria, outcome definition, exposure definition, risk adjustment, possible sources of confounding, assessment of data, crude OR (95% CI) report, and adjusted OR (95% CI) report.
2.4. Statistical analysis
We performed several subgroup analyses to investigate the association between tattooing and hepatitis C among different populations. We conducted subgroup analyses based on the study population and study design (case–control, cohort, and cross-sectional). We also grouped studies into eight main mutually exclusive subgroups including: community samples, blood donors, hospital samples, injection drug users (IDUs), non-injection drug users (non-IDUs), drug users, prisoners, and high-risk population (street youth, HIV patients, tattooed in non-professional shops, and reused tattoo needles).
For all analyses, we weighted the study-specific adjusted log ORs by the inverse of their variances. Both fixed and random effect models were used to estimate the pooled adjusted OR. Statistical heterogeneity between studies was evaluated with Cochran's Q test and the I2 statistic. 17 A sensitivity analysis was carried out to assess the individual influence of studies, and the analysis repeated excluding the studies with the largest weights. We used a funnel plot 18 and Egger's test 19 to assess the presence of publication bias. Statistical analyses and graphs were performed with RevMan 5 (Review Manager, version 5.0., The Cochrane Collaboration, 2008) and HEpiMA (Compute Methods Programs Biomed).
3. Results
Figure 1 shows the results of our search strategy and step-by-step inclusion and exclusion of the retrieved papers. Appendix A represents the search strategy used in this study. We identified a total of 1299 citations related to risk factors of hepatitis. A total of 272 studies were excluded as duplicates, 717 studies were excluded after reviewing titles, 170 excluded after reviewing abstracts, and 16 were excluded after reviewing the full text. A final number of 124 papers from 30 countries that reported an association between tattooing and the risk of transmission of hepatitis C were included in this systematic review (Appendix B).
- Figure 1.Selection of studies for inclusion in the systematic review and meta-analysis.
Walang komento:
Mag-post ng isang Komento