Treatment Of Acne Scars With Ablative Fractional Co₂ Laser:A Two-year Follow Up Study Of 83 Patients

Background:Acne scars often affect the appearance and psychology of patients,and there are many methods for treating acne scars.The fractional CO₂ laser had been proved to be a potent therapeutic alternative for the management of acne scars and reports with long-term evaluation were required.Objective:This study was designed for long-term follow-up to investigate the efficacy and related contributing factors of fractional CO₂ laser in treating acne scars patients.Methods:This study was a retrospective study of 83 patients with acne scars who were recruited in the laser cosmetic department of Shandong Dermatology Hospital from 2012 to2016.They all received fractional CO₂ laser treatment with an energy of 75 mJ and a dot spacing of 1.2 mm.The shape and size of the spot were determined by the lesion area.The most common shape was 20 mm×20 mm square.Each treatment interval was 2-3 months,and the patient was reviewed and re-photographed 2-3 months after the last treatment.Two dermatologists who did not participate in the treatment calculated the ECCA score and the4-level scale improvement according to the photos before and after treatment;the patient’s self-satisfaction was observed by telephone follow-up 2 years after the last treatment.Results:The average treatment times were 2.7±1.2 and the mean ECCA score after treatment was 72.15±31.33 compared with the baseline（t=7.766,P<0.001）.The total effective rate was 39.76%;3.61%with less than 25%improvement,56.63%with 26-50%improvement,34.94%with 51-75%improvement and 4.82%with more than 75%improvement.The total satisfaction rate was 48.19%bases on the participants’self assessment.By analyzing the rate of reduction in ECCA scores,we found a correlation between acne scar type and fractional CO₂ laser treatment（P=0.010）:the best response to treatment was rolling acne scars,and the worst response to treatment was iced acne scars（P=0.035）;by analyzing the degree of clinical improvement,it was found that different types of acne scars have different clinical improvement（χ²=23.130,P<0.001）:rolling acne scars are better than iced acne scars,and the difference was statistically significant（P=0.002）.By analyzing the reduction rate of ECCA scores,we found a correlation between the number of different treatments and the effect of fractional CO₂ laser treatment（P<0.05）:patients treated 3,4,and 5 times were better than patients treated 1 or 2 times（P<0.05）;by analyzing the degree of clinical improvement,it was found that there was a correlation between the number of treatments and the degree of clinical improvement（P<0.05）:the clinical improvement of patients treated 3,4,and 5 times was better than that of treatment 1 time.The clinical improvement of patients treated 4 or 5 times was better than that of treatment 2 times（P<0.05）.Conclusion:The fractional CO₂ laser can effectively improve acne scars without obvious permanent adverse reactions.Clinical response and treatment effects are influenced by many factors,such as different types of acne scars and different treatment times,with different curative effects:superficial acne scars such as rolling scars are better than ice cone scars;more treatments are more effective.