187295 Homicide rates in Philadelphia: Contribution of age distribution to rate differences

Wednesday, October 29, 2008

Suet Lim, PhD , Community Behavioral Health, Philadelphia Department of Behavioral Health, Philadelphia, PA
Cynthia L. Line, PhD , Division of Maternal, Child and Family Health, Philadelphia Department of Public Health, Philadelphia, PA
Rebecca Drake , Health Data, Statistics and Research, Philadelphia Department of Public Health, Philadelphia, PA
Jessica M. Robbins, PhD , Division of Ambulatory Health Services, Philadelphia Department of Public Health, Philadelphia, PA
In an effort to put the recent increase of homicides in context, we compared Philadelphia trends over a 25 year period to U.S. and several large cities, including Boston, Chicago, NYC and D.C. In comparison, Philadelphia rates are consistently higher than the U.S., Boston, and NYC but lower than D.C. Homicide rates peaked in 1985 to 1996, and the 2000s saw stable rates for most of the cities. However, in contrast to the general pattern, Philadelphia rates started to increase in the 2000s. Criminal justice literature on youth violence suggested several themes, including cohort size that can contribute to rate variability. To measure the contribution of age distribution to the recent increase of homicides in Philadelphia, we performed decomposition analysis on Black Male crude homicide rates between 2000 and 2006. Of the sharp increase in rates between 2005 and 2006, decomposition indicates that 80% of the increase was due to differences in the rates' schedules. Age distribution differences only accounted for 20% of the increase. Between 2000 and 2005, age distribution differences accounted for 70% of the increase. Each successive year between 2000 and 2006, the cohorts for the 15-19, 20-24, 25-29 age-groups grew. The relative size of these cohorts played a larger role in the increase in rates in the first half of the 21st century but 2006 is a different story. In considering homicide trends and patterns, there is a need to examine the contribution of demographic factors such as relative cohort size.

Learning Objectives:
1. Describe homicide trends in Philadelphia and comparative cities over 25 years period 2. Apply rate decomposition technique 3. Assess the contribution of age distribution to rate difference

Keywords: Violence, Epidemiology

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I conduct public health research for Philadelphia Department of Public Health and has over ten years in vital statistics and epidemiology work.
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.