By Liz Highleyman

Siavash Jafari from the University of British Columbia School of Population and Public Health and colleagues performed a systematic literature review to determine whether tattooing is a risk factor for the hepatitis C transmission.

Tattoos have become increasingly popular in recent years, the study authors noted as background. In the U.S., an estimated 36% of people under age 30 have tattoos. In Canada, approximately 8% of high school students have at least one tattoo, while 21% of those who don't have one want one. Among prisoners, an estimated 25%-35% have tattoos.

Tattooing involves injection of pigments into the dermal layer of skin. This is typically done using a machine with multiple needles that puncture the skin 80-150 times per second, but amateur tattoos may also be done by hand using a single needle or other sharpened implement.

"Since tattoo instruments come in contact with blood and bodily fluids, infections may be transmitted if instruments are used on more than one person without being sterilized or without proper hygiene techniques," Jafari said in a University of British Columbia press release.

Tattoo needles and other equipment can potential transmit HCV, hepatitis B virus (HBV), HIV, and other blood-borne pathogens. Professional tattooists in the U.S. today use single-use needles, sterilized or single-use ink holders, and inks formulated specially for tattooing, as well as employing universal blood-borne pathogen precautions such as wearing latex gloves; do-it-yourself tattoos and those done in settings such as prisons, however, often do not follow such precautions.

The investigators searched medical literature databases including MEDLINE, PUBMED, and EMBASE to identify all case-control, cohort, and cross-sectional studies published prior to November 2008 that evaluated risks related to tattooing or risk factors for HCV transmission.

A total of 124 studies from more than 30 countries -- including Canada, the U.S., Australia, Brazil, Italy, and Iran -- were included in the systematic review. Of these, 83 studies (45 cross-sectional, 30 case-control, and 8 cohort) were used for the meta-analysis, representing a total 132,145 participants.

Results

	Tattooing was associated with nearly a 3-fold increased likelihood of HCV infection overall (pooled odds ratio [OR] 2.74).
	A sub-group analysis showed that the strongest association between tattooing and HCV risk was seen among people who do not inject drugs (OR 5.74).
	Tattooing was also associated with elevated HCV risk in other sub-groups:
	Blood donors: OR 3.73; Hospital patients: OR 3.20; Injection drug users: OR 3.06; "High-risk" populations: OR 2.80; Community samples: OR 2.79; Prisoners: OR 2.56; Users of any type of drugs: OR 2.30.
	The association between tattoos and HCV infection was seen for both professionally done tattoos and those done in non-professional facilities or by friends (OR 2.80).
	The association held in another analysis that excluded 11 studies with the widest confidence intervals, indicating more uncertainty about whether the results were due to chance.

"Findings from the current meta-analysis indicate that tattooing is associated with a higher risk of hepatitis C infection," the study authors concluded. "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."

"The strength of our review is mainly in the large number of studies and multinational nature of the study participants," they elaborated in their discussion. "In light of the observational nature of the studies in this review, the association between tattooing and hepatitis was strong in all subgroups and consistent across all study designs."

"We believe that having a tattoo is a strong risk factor for transmission of hepatitis C for two reasons," they continued. "First, several studies have reported an association between tattooing and other infections including HIV, hepatitis B, leprosy, and methicillin-resistant Staphylococcus aureus [MRSA]. Secondly, some studies have shown that the risk of hepatitis infection increases with the increase in the surface area covered by a tattoo, as well as the number of tattoos received by an individual."

The authors also noted other potential risks of tattooing besides blood-borne pathogens, including bacterial and fungal infections, allergic reactions, toxic ingredients in tattoo inks, unknown risks of new glow-in-the-dark or black-light inks, and risks associated with tattoo removal.

In addition to prevention awareness efforts for tattoo recipients, the researchers called for risk-reduction education for tattoo artists, infection-control guidelines enforced through inspections, and better adverse event reporting and record-keeping. They also suggested that clinicians might consider HCV screening for their patients with tattoos.

Investigator affiliations: British Columbia Centre for Disease Control; Community Medicine, University of British Columbia; British Columbia Children's Hospital; Centre for Clinical Epidemiology and Evaluation, Vancouver Hospital, Vancouver, British Columbia, Canada.

Reference
S Jafari, R Copes, S Baharlou, and others. Tattooing and the risk of transmission of hepatitis C: a systematic review and meta-analysis. International Journal of Infectious Diseases. July 31, 2010 (Epub ahead of print).

Other Source
University of British Columbia. Tattooing linked to higher risk of hepatitis C: UBC study. Press release. August 6, 2010.