title: Gender Differences in Predrinking Behavior Among Nightclubs' Patrons.
abstract: BACKGROUND
  Drinking before entering nightclubs (predrinking) seems to be associated with an increase in alcohol-related harm. This study aims to investigate gender differences in predrinking behavior and to evaluate its association with risk behaviors practiced inside nightclubs.
  
  
  METHODS
  Individual-level data were collected by a portal survey of 2,422 patrons at the entrance and 1,833 patrons at the exit of 31 nightclubs located at São Paulo, Brazil. The nightclubs were selected by 2-stage sampling with probability proportional to the establishments' capacity in the first stage and a systematic sample of patrons in the entrance line in the second stage. Breath alcohol concentration (BrAC) was measured at the entrance and exit. Face-to-face interviews identified predrinking characteristics and risk behaviors. Weighted analyses were stratified by gender.
  
  
  RESULTS
  Predrinking was practiced by 49.2% (95% confidence interval [CI] = 42.7 to 55.8) of the male patrons and 29.0% (95% CI = 20.6 to 38.9) of the female patrons (p < 0.001) on the day of the interview. When considering only predrinkers, men and women showed similar BrAC at entrance and exit and similar proportion of alcoholic intoxication (BrAC ≥ 0.38 mg/l). In both genders, people who practiced predrinking on the day of the interview were more likely to drink inside the nightclub, compared to those who did not practice predrinking (p < 0.001). Among men, the practice of predrinking increased the chance of "drinking and driving" after leaving the nightclub (odds ratio [OR] = 6.9, 95% CI = 4.1-11.5, p < 0.001). Among women, the practice of predrinking increased the chances of experiencing sexual harassment in the nightclub (OR = 2.9, 95% CI = 1.3 to 6.6, p = 0.010).
  
  
  CONCLUSIONS
  Predrinking is more prevalent among men; however, men and women who engaged in predrinking have a similar pattern of alcohol consumption and exit BrAC. The fact that risk behaviors and illicit drug use were associated with predrinking but differ between genders suggests that a gender-specific approach should be used in tailored interventions to prevent alcohol-related harm in nightclubs.
authors.affiliation: Department of Preventive Medicine, Section of Epidemiology, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Mariana G R
authors.initials: MG
authors.lastname: Santos
authors.affiliation: Department of Information in Health, Section of Statistics, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Angela T
authors.initials: AT
authors.lastname: Paes
authors.affiliation: Department of Preventive Medicine, Section of Biostatistics, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Adriana
authors.initials: A
authors.lastname: Sanudo
authors.affiliation: Department of Preventive Medicine, Section of Biostatistics, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Solange
authors.initials: S
authors.lastname: Andreoni
authors.affiliation: Department of Preventive Medicine, Section of Epidemiology, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Zila M
authors.initials: ZM
authors.lastname: Sanchez
mesh_terms: D000293:Adolescent; D000328:Adult; D000428:Alcohol Drinking / Q000453:epidemiology* / Q000523:psychology; D001938:Brazil / Q000453:epidemiology; D003617:Dangerous Behavior; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012309:Risk-Taking; D012727:Sex Characteristics; D055815:Young Adult
keywords: Alcohol; Brazil; Epidemiology; Predrinking; Risk Behaviors