Response to Narrow-band UVB – Vitiligo-melasma versus Vitiligo

A Comparative Study

Parikshit Sharma; Harsha S. Pai; Ganesh S. Pai; Maria Kuruvila; Reshma Kolar

Disclosures

Am J Clin Dermatol. 2011;12(2):127-132. 

In This Article

Results

Of the 39 patients with vitiligo, melasma was present in 18 patients (46.15%). Ten of these patients (55.56%) had a malar pattern and eight patients (44.44%) had a central facial pattern of melasma (figures 1 and 2). None of the patients was aware of the exact duration of or trigger for themelasma as their presenting complaint was depigmentation. The peak age of onset for patients in the vitiligo group was between 11 and 20 years, whereas the peak age of onset for patients in the vitiligo-melasma group was between 41 and 50 years (table II).

Figure 1.

Coexisting vitiligo and melasma.

Figure 2.

Coexisting vitiligo and malar melasma.

The precipitating/aggravating factors reported for vitiligo were trauma (six patients; 15.4%), pregnancy (two patients; 5.1%), and surgery (one patient; 2.6%).

Facial Pigmentation

At the end of 12 weeks, 86% of patients in the vitiligo-melasma group attained ≥75% pigmentation compared with only 12.5% of patients in the vitiligo group (table III). Repigmentation appeared earlier in the vitiligo-melasma group; all patients in the vitiligo-melasma group started developing visible pigmentation by 4 weeks compared with only 50% of patients in the vitiligo group.

On analyzing the overall improvement using the Friedman test, the p-value was 0.002 for each group, which shows a statistically significant improvement in each group after 12weeks of phototherapy compared with the corresponding pre-treatment condition.

Intra-group week-wise improvement was gauged using the Wilcoxon test. In the vitiligo-melasma group, the improvement between week 4 and week 8 was statistically significant (p = 0.027), as was the improvement between week 8 and week 12 (p = 0.023). In the vitiligo group, the improvement between week 4 and week 8 was not statistically significant (p = 0.066), whereas the improvement between week 8 and week 12 was significant (p = 0.026). The smaller p-values in the vitiligo-melasma group show that the improvements were statistically more significant than those in the vitiligo group.

When an intergroup comparison was made at weeks 4, 8, and 12, the p-value for the week 4 improvement comparison was 0.072, which showed that the difference was not statistically significant although a clinically significant difference existed between the two groups. At weeks 8 and 12, the p-values were 0.001 and 0.004, respectively, which showed significantly superior improvements on the face in the vitiligo-melasma group compared with the vitiligo group. This correlated with our clinical observations.

On evaluating the median facial pigmentation of the individual patients from both groups, the vitiligo-melasma group showed an improvement in the median from 10% to 75% whereas in the vitiligo group the median increased from 5% to 37.5% (figure 3).

Figure 3.

Improvement in facial pigmentation in the vitiligo-melasma and vitiligo groups.

Limb Pigmentation

Over the limbs, nearly 75% of patients in the vitiligo-melasma group attained 75% or more pigmentation at the end of 12 weeks compared with only 9% of patients in the vitiligo group (table IV). Also, 100% of the patients in the vitiligo-melasma group started repigmenting by the fourth week whereas only 55% of their vitiligo group counterparts demonstrated visible pigmentation at week 4.

There was a statistically significant overall improvement in limb pigmentation in both groups after 12 weeks of phototherapy compared with their corresponding pre-treatment condition (Friedman test; p = 0.000 for both groups).

Intra-group week-wise improvement was gauged using the Wilcoxon test. In the vitiligo-melasma group, there were significant improvements from week 4 to week 8 (p = 0.011) and from week 8 to week 12 (p = 0.011). In the vitiligo group, the improvements from week 4 to week 8, and from week 8 to week 12 were also significant (p = 0.011 and p = 0.027, respectively). The smaller p-values in the vitiligo-melasma group show that the improvements were statistically more significant than in the vitiligo group.

Intergroup comparisons at weeks 4, 8, and 12 showed a significantly superior improvement over the limbs in the vitiligo-melasma group compared with the vitiligo group (p = 0.0002, p = 0.005, and p = 0.002, respectively). This correlated with our clinical observations.

In the vitiligo-melasma group there was an improvement in the median limb pigmentation from 25% at baseline to 75% after 12 weeks, whereas in the vitiligo group the median improved from 10% to 50% (figure 4).

Figure 4.

Improvement in limb pigmentation in the vitiligo-melasma and vitiligo groups.

Trunk Pigmentation

In the vitiligo-melasma group, only 20% of patients showed ≥75% pigmentation at week 12; the remainder had 50% pigmentation or less (table V). In the vitiligo group, 62.5% of patients showed ≥75% pigmentation at the end of 12 weeks. Surprisingly, the vitiligo group responded better over the trunk.

However, as with the face and limbs, the patients in the vitiligo-melasma group started repigmenting earlier on the trunk although the final pigmentation level reached was less than their vitiligo group counterparts.

There was a statistically significant overall improvement in both groups after 12 weeks of phototherapy compared with their corresponding pre-treatment condition (Friedman test; p = 0.022 in the vitiligo-melasma group and p = 0.001 in the vitiligo group).

Analysis of intra-group week-wise improvement using the Wilcoxon test showed that the improvement was not statistically significant in the vitiligo-melasma group from week 4 to week 8 (p = 0.083) or week 8 toweek 12 (p = 0.059).However, a clinically significant improvement was noted. In the vitiligo group, the improvement was statistically significant for both time periods (p = 0.017 for both). The lower p-values in the vitiligo group show that it had statistically more significant improvements than the vitiligo-melasma group.

Intergroup comparison of individual pigmentation at weeks 4, 8, and 12 showed no statistically significant differences in improvement between the two groups. However, a clinically significant difference was noted from the median trunk pigmentation values. In the vitiligo-melasma group the median improved from 10% at the initiation of treatment to 50% at the end of 12 weeks whereas in the vitiligo group the median improved from 25% to 75% (figure 5).

Figure 5.

Improvement in trunk pigmentation in the vitiligo-melasma and vitiligo groups.

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