Trends in nonpolio acute flaccid paralysis incidence in India 2000 to 2013
Pediatrics. 2015 Feb;135 Suppl 1:S16-7. doi: 10.1542/peds.2014-3330DD. PMID: 26005734
Trends in Non-Polio Acute Flaccid Paralysis incidence in India 2000-2013
N. Vashisht
J.M. Puliyel*
V. Sreenivas**
Department of Pediatrics, Jaypee Hospital, Sector-128, Noida,GautamBuddh Nagar-201304, UP
*Department of Pediatrics, St. Stephen's Hospital, Tis Hazari, Delhi 110054, India
**Department of Biostatistics, All India Institute of Medical Sciences, New Delhi – 110029, India
Short title: Non-Polio Acute Flaccid Paralysis
Key words: Acute flaccid paralysis, surveillance, vaccination, polio.
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Introduction: Although the incidence of polio acute flaccid paralysis (AFP) has come down in India, the non-polio AFP (NPAFP) rate has increased. Nationwide, the NPAFP rate is 11.82/100,000 where the expected rate is 1-2/100,000. We examined the correlates of NPAFP, to discern explanations for the increase.
Purpose: The incidence of polio AFP has come down in the country. As a consequence the total AFP rate (which includes polio and non-polio causes of AFP) must come down with the non-polio AFP rate remaining steady.Inexplicably however, the non-polio AFP rate has shown a trend to increase over the years from 2000.
Materials and Methods: The data on AFP, polio and non-polio AFP and number of polio rounds were examined in each state in each year from 2000 to 2013.Data from the National Polio Surveillance web site was used. Multiple linear regression analysis adjusting for region/state, total and female literacy rate, population density and per-capita GDP was performed.Differences between states and changes over time were analyzed.
Results: NPAFP increased with the number of OPV doses used. (R2=25.02%;P<0.001).When effect of cumulative doses over the previous years was examined, the non-polio AFP rate in 2013 best correlated to the cumulative doses received in the previous 7 years (R2=57.16%), excluding 2012 as data for this year was incomplete.This correlation was highly significant (P<0.001). On multiple regression analysis, the number of OPV doses was the only factor that showed a positive correlation with the NPAFP rate.The average increase in the non-polio AFP rate was 1.31 per 100,000 (P<0.001, 95% CI: 1.11-1.52) with each dose of OPV. The NPAFPrate in UP and Bihar which had consistently increased year on year till 2011, decreased in the two states in 2012, coinciding with a reduction in doses of OPV administered.
Conclusions: Our results indicate that the incidence of non-polio AFP was strongly associated with the number of OPV doses delivered to the area. A dose response relation with cumulative doses over the years was also observed, which further strengthens the hypothetical relationship between polio vaccine and non-polio AFP. The fall in the NPAFP rate in Bihar and UP for the first time in 2012, with a decrease in the number of OPV doses delivered, is further corroborative evidence of a causative association between OPV doses and the NPAFP rate.