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CORRESPONDENCE |
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| Year : 2014 | Volume
: 59
| Issue : 5 | Page : 516-517 |
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| Authors' Reply |
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N Asokan1, Priya Prathap1, PP Rejani2
1 Department of Dermatology and Venereology, Government Medical College, Thrissur, Kerala, India
2 Department of Psychiatry, Government Medical College, Thrissur, Kerala, India
| Date of Web Publication | 1-Sep-2014 |
Correspondence Address:
N Asokan
Department of Dermatology and Venereology, Government Medical College, Thrissur, Kerala
India
 Source of Support: None, Conflict of Interest: None  | Check |
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How to cite this article:
Asokan N, Prathap P, Rejani P P. Authors' Reply. Indian J Dermatol 2014;59:516-7 |
Sir,
We thank Mr. Ho and Mr. Antrum for the interest shown in our article and the in-depth analysis of it. The queries raised by them give us an opportunity to explain more about the methods and conclusions of our study. [1]
- It is true that Psoriasis Area and Severity Index (PASI) was not normally distributed in our study population, but skewed to the left; similar to the observations in most case series. Cut off value of PASI to define severity of psoriasis was suggested as '12 or above' in a previous study [2] and 'above 10' in another. [3] We considered that categorizing the study population into less severe and more severe using the third quartile will be better than depending on any pre-determined cut off value. This would make the definition of severity more relevant to our study population and therefore less arbitrary. Patients in the highest quarter of severity could unarguably be considered as having more severe disease. It may be noted that the cut off value we obtained (13.88) was close to the values suggested earlier. It may also be noted that median and quartiles are less sensitive to extreme values when compared with mean and hence are more appropriate to analyze skewed data.
- Though smoking and alcohol have been found to be confounding factors for several outcome measures, including in various studies on psoriasis; our data showed that alcohol by itself was not affecting severity, except when combined with smoking. Separate analysis for each group-smokers only, alcohol users only and those who smoked and consumed alcohol-showed that Odd's ratio (OR) for severity of those who had both habits was significant at 1.77 (CI = 1.06, 2.96); but that was mostly contributed by 'smoking only group' with OR = 1.69 (CI = 1.03, 2.77), rather than by 'alcohol use alone group' which was not significant with OR = 1.13 (CI = 0.69, 1.85). So alcohol use was not considered a confounding factor in our study.
- Any possible impact on severity of psoriasis due to substance use is a result of the biological changes induced by it. So, we thought that it would be more appropriate to use instruments which would reflect such changes more effectively, rather than just quantitative measures as provided by cigarette pack years or alcohol units. This indeed was a deliberately introduced novelty in the design of this study. We agree with Mr. Ho and Mr. Antrum that it would be of interest to study the effects of smoking cessation on severity of psoriasis and look forward to studies designed for that purpose in future.
 References | |  |
| 1. | Ho JK, Antrum JH. Comment on: Asokan N, et al. "Severity of psoriasis among adult males is associated with smoking, not with alcohol use. Indian J Dermatol 2014;59:5. 
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| 2. | Feldman SR. A quantitative definition of severe psoriasis for use in clinical trials. J Dermatolog Treat 2004;15:27-9.
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| 3. | Finlay AY. Current severe psoriasis and the rule of tens. Br J Dermatol 2005;152:861-7.
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