Objective: To analyze variables affecting the treatment course and prognosis of Q-switched laser tattoo removal. Design: Observational prospective cohort study. Setting: The study was carried out in a referral center for surgery and laser surgery in Milan. Participants: Of 397 consecutive patients initially enrolled from January 1, 1995, to December 31, 2010, 352 patients (201 men and 151 women; median age, 30 years) were included in the analysis. Intervention: All patients were treated by the same investigator with Q-switched 1064/532-nm Nd:YAG laser and Q-switched 755-nm alexandrite laser according to tattoo colors. Laser sessions were scheduled at 6-week or longer intervals. Main Outcome Measures: Successful therapy was defined as removal of the tattoo, with no adverse effects other than transient hypochromia or darkening. Results: The cumulative rates of patients with successful tattoo removal were 47.2% (95% CI, 41.8%-52.5%) after 10 sessions and 74.8% (95% CI, 68.9%-80.7%) after 15 sessions. Smoking, the presence of colors other than black and red, a tattoo larger than 30 cm2, a tattoo located on the feet or legs or older than 36 months, high color density, treatment intervals of 8 weeks or less, and development of a darkening phenomenon were associated with a reduced clinical response to treatment. Conclusions: To our knowledge, this study is the first to formally assess prognostic factors for effective tattoo removal by Q-switched laser. Several variables influence response rates and should be considered when planning tattoo removal treatments.
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