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Various methods for clinical evaluation of the effect of treatment of acne vulgaris have been studied. Counting of acne lesions was found to be more sensitive than the opinion of the patients and the assessment of colour photographs. The correlation between the results obtained by lesion counts and evaluation by photographs was low, as was also the reproducibility of photographic assessment. This methodological study was performed during a 6 week period, using a double-blind technique for comparing the effect of 0.6 g of oral zinc sulphate daily versus placebo in 54 patients. With zinc treatment acne improved with about one third as rated with a score system. Compared to placebo this result is slightly better (p less than 0.05). Inflammatory acne of grades 2-3 responded more favourably than comedonal acne to zinc treatment.
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Lidén et al. (1980) studied this question.
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