The 130th Annual Meeting of APHA

Abstract #46290

Paul G Devereux, PhD¹, Mary Guinan, MD, PhD², Anpalaki Ragavan, MS¹, Richard Whitley, MS², and Jeff Vollman, MPA². (1) Department of Health Ecology, University of Nevada, Mail Stop/274, Lombardi Building, Reno, NV 89557, (775) 784-4041 x-227, devereux@unr.edu, (2) State of Nevada Health Division, 505 E. King Street, Carson City, NV 89701

The objectives of this presentation are to address issues about methods for calculating prevalence rates and provide suggestions to improve accuracy. CDC calculates prevalence rates using population figures from the previous year. This calculation method does not account for changes in population growth and overestimates the rate from states with small, rapidly growing populations. For example, the 1998 gonorrhea rate based on Nevada’s 1997 population, reported by CDC, is 86.2 per 100,000 people. The 1998 rate using Nevada’s 1998 population drops from 86.2 to 82.7, a statistically significant decrease ([95% CI]=2.9, 4.1). Because current population figures may not be available, CDC could use a population estimate that includes the percentage increase in the projected population rather than ignoring any population changes when using the previous year’s population figure. For example, if the 3.8% projected increase in Nevada’s population from 1998 to 1999 was included in the available 1998 population figure, the 1999 rate would be 71.9. Using the 71.9 rate calculated with the projected growth included, there is no longer a significant difference between the 1999 rate initially published by CDC (74.6) and the revised rate of 72.0 reported by CDC after the population figure for that year became available ([95% CI]=.45, -.65). We recommend that CDC use the forecasted population figure for that year rather than the population figure from the previous year.

Learning Objectives:

• After this session, the participant will be better able to identify measurement issues in calculating prevalence rates.

Keywords: Epidemiology, Data/Surveillance

Presenting author's disclosure statement:
I do not have any significant financial interest/arrangement or affiliation with any organization/institution whose products or services are being discussed in this session.