The development of the Police Practices Scale: Understanding policing approaches towards street-based female sex workers in a U.S. City.

Policing is an important structural determinant of HIV and other health risks faced by vulnerable populations, including people who sell sex and use drugs, though the role of routine police encounters is not well understood. Given the influence of policing on the risk environment of these groups, methods of measuring the aggregate impact of routine policing practices are urgently required. We developed and validated a novel, brief scale to measure police patrol practices (Police Practices Scale, PPS) among 250 street-based female sex workers (FSW) in Baltimore, Maryland, an urban setting with high levels of illegal drug activity. PPS items were developed from existing theory and ethnography with police and their encounters with FSW, and measured frequency of recent (past 3 months) police encounters. The 6-item scale was developed using exploratory factor analysis after examining the properties of the original 11 items. Confirmatory factor analysis was used to model the factor structure. A 2-factor model emerged, with law enforcement PPS items and police assistance PPS items loading on separate factors. Linear regression models were used to explore the relative distribution of these police encounters among FSW by modeling association with key socio-demographic and behavioral characteristics of the sample. Higher exposure to policing was observed among FSW who were homeless (β = 0.71, p = 0.037), in daily sex work (β = 1.32, p = 0.026), arrested in the past 12 months (β = 1.44, p<0.001) or injecting drugs in the past 3 months (β = 1.04, p<0.001). The PPS provides an important and novel contribution in measuring aggregate exposure to routine policing, though further validation is required. This scale could be used to evaluate the impact of policing on vulnerable populations' health outcomes, including HIV risk.