Just How Good Is Your Rule of Thumb? Validating Male-to-Female Gonorrhea Case Ratio As a Proxy for MSM-Involved Epidemics at the County Level

Stenger, Mark

Wednesday, September 21, 2016: 3:00 PM

Salon C

Mark Stenger, MA, DSTDP/Surveillance and Data Management Branch, CDC, Atlanta, GA, Heidi Bauer, MD, MS, MPH, STD Control Branch, California Department of Public Health, Richmond, CA, Margaret Eaglin, MPH, MUPP, HIV/STI Bureau, City of Chicago Department of Public Health, Chicago, IL, Megan Jespersen, MPH, Infectious Disease Epidemiology Program, LA Office of Public Health, New Orleans, LA, Robbie Madera, MPH, Philadelphia Department of Public Health, Philadelphia, PA, Mukhtar Mohamed, MPH, MA, STD Control Program, Connecticut Department of Public Health, Hartford, CT, Robert P. Kohn, MPH, Applied Research, Community Health, Epidemiology, and Surveillance (ARCHES) Branch, Population Health Division, San Francisco Department of Public Health, San Francisco, CA, River Pugsley, PhD, MPH, Division of Disease Prevention - STD Surveillance, Operations and Data Administration, Virginia Department of Health, Richmond, VA, Irina Tabidze, MD, MPH, Division STI/HIV, Chicago Department of Public Health, Chicago, IL and Elizabeth Torrone, MSPH, PhD, Division of STD Prevention, Centers for Disease Control and Prevention, Atlanta, GA

Background:Reported incidence of Neisseria gonorrhoeae increased during 2009–2014 from 98.1 to 110.7 cases per 100,000. Observed increases were steeper among men. Evidence also suggests that gonorrhea is increasing among men who have sex with men (MSM). Lacking other information, STD programs in the US have traditionally used crude measures such as the male-to-female case ratio (MFCR) as a rule of thumb to assess the degree of MSM involvement in local epidemics. This indicator of MSM involvement in gonorrhea incidence has not previously been validated.

Methods:A random sample of cases reported 1/2010 through 6/2013 were interviewed in counties participating in the STD Surveillance Network (SSuN). MSM status and incidence of commercial sex work were ascertained for sampled cases. Data were pooled across the period, weighted and estimates of proportion of cases attributable to MSM behavior and proportion reporting sex work were calculated for counties reporting ≥100 cases in the time period with at least 10% cases interviewed. The MFCR was assessed using general linear models and Pearson’s partial correlation for association with the estimated proportion attributable to MSM while controlling for reported sex work.

Results:56 counties met the inclusion threshold (N=85,445 cases); MFCR ranged from 0.66 to 8.7 and the proportion of total cases attributable to MSM varied from 2.5% to 62.3%. MFCR was strongly correlated with proportion of cases attributable to MSM after controlling for commercial sex work (Pearson’s partial r=0.754, P<0.0001). A MFCR threshold of 1.25 or greater correctly identified 75% of counties with MSM incidence exceeding 30% of all cases.

Conclusions:Our data suggest that the MFCR for gonorrhea at the county level is a valid indicator of MSM involvement and could be used by STD programs to tailor their local programmatic mix to include MSM-specific interventions where indicated.

2A1 Just How Good Is Your Rule of Thumb? Validating Male-to-Female Gonorrhea Case Ratio As a Proxy for MSM-Involved Epidemics at the County Level