Authors' reply.

Sir,

We thank authors of this letter for their interest in our article and their critical appraisal of our work. We would like to offer certain clarification of the points they have raised in the letter.[1]

Regarding specific response parameters and patient specific parameters we acknowledge that we did not provide details in our article due to constraints of space. The same applies to not providing blood collection and serum preparation techniques. However, we would like to state that we did use the urticaria activity score (UAS) as a specific response parameter.

UAS showed a declining trend from baseline (mean 36 ± 6) to 4 weeks (mean 25 ± 5) and further decrease to 9 weeks (mean 10 ± 6, P = 0.001). Dermatology life quality index (DLQI) also showed a significant decline from baseline (mean 26 ± 6) to 9 weeks (mean 10 ± 6). The no. of antihistamine consumption at baseline (mean 7 ± 1) and 9 weeks (mean 2 ± 1, P = 0.001) also decreased accordingly (mean 2 ± 1, P = 0.001).

Thus summarize the result according to UAS: 45% patients had excellent response and 30% pt had moderate response and 25% pt had mild response at the end of 9 weeks.

Similarly, DLQI and the average no. of antihistamines use from baseline to 9 weeks had also declined significantly.

The thyroid profile showed deranged thyroid profile in 4 patients, but not associated with anti-microsomal thyroid antibody; along with it all patients were antinuclear antibody negative. As autologous serum was used and not involving foreign serum; hence, we did not think it economically feasible to do all tests by the author.

Regarding the procedure our method of collection of serum and injection of the same was based on standard and accepted techniques as mentioned by Bajaj et al. 5 ml blood was collected in a red topped vacutainer and then further centrifuged at 3,000 rpm, made into serum and 2.5 ml is injected deep intramuscularly immediately. No other special techniques were used for the collection and administration.[2]

The duration of auto-serum therapy was based on the work of Staubach et al. who found good results weekly injections for 8 weeks.[3]

Action of auto-serum therapy in chronic urticaria is based on the principle that it has immunomodulating effects that elicit a beneficial response. As mentioned in the article, it leads to desensitization by activating reticuloendothelial system with formation of specific antibodies. It is now believed that it affects immune parameters such as interleukin-10, T cell subpopulation and activation of macrophages.[4]

We acknowledge we did not mention the length of follow-up in our article and wish to express regrets for the same. Now, we would like to mention that the duration of follow-up ranged from 1 year to 3 years. We chose a longer follow-up duration to accurately assess the longevity of the suppressive effect of this therapy.

All patients were stopped with antihistamines and other immunosuppressive drugs 2 days prior the autologous serum skin test and during the treatment patients were given rescue antihistamine whenever required so that the average number of tablets required could be calculated and used to monitor the response to therapy.

In all standard references we pursued there were no significant side-effects detected. Hence, we feel that the safety and probably the efficacy of this therapy are self-evident. Obviously, this has to be validated by larger trials, which are double blind in nature.

We cannot deny that omalizumab is a well-tolerated and effective drug for chronic urticaria. However, beyond the reach of most of the Indian patients, we feel that using auto-serum therapy would be a cost-effective, cheap and safe way to treat chronic spontaneous urticariain patients who cannot afford omalizumab.