Table 3

Factors associated with inconsistent condom use in 4014 casual partnerships among 1707 heterosexuals attending the sexually transmitted infections outpatient clinic, Amsterdam, 2010

OR (95% CI)p ValueaOR (95% CI)p Value
Individual participant characteristics
Gender0.0610.140
 Male11
 Female1.17 (0.99 to 1.37)1.15 (0.95 to 1.39)
Ethnicity0.0980.320
 Dutch11
 Surinamese/Antillean0.77 (0.58 to 1.03)0.79 (0.58 to 1.08)
 Other0.83 (0.64 to 1.07)1.02 (0.78 to 1.34)
Age in years*0.0030.097
 201.08 (0.87 to 1.35)1.17 (0.92 to 1.48)
 251.08 (0.92 to 1.26)1.10 (0.94 to 1.28)
 3011
 350.90 (0.81 to 1.03)0.93 (0.81 to 1.07)
 400.79 (0.67 to 0.94)0.85 (0.69 to 1.04)
Education0.2600.005
 High11
 Low1.11 (0.93 to 1.32)1.33 (1.09 to 1.62)
Total no. of partners in the year preceding study participation*0.1600.020
 111
 20.70 (0.45 to 1.09)0.77 (0.59 to 0.99)
 40.52 (0.27 to 1.03)0.65 (0.49 to 0.85)
 80.53 (0.29 to 0.98)0.66 (0.48 to 0.89)
Characteristics of the partnership
Age difference in years*,‡<0.0010.018
 −100.80 (0.64 to 1.01)0.72 (0.57 to 0.91)
 −50.80 (0.66 to 0.96)0.75 (0.62 to 0.91)
 011
 50.94 (0.79 to 1.13)1.00 (0.81 to 1.24)
 100.77 (0.61 to 0.97)0.89 (0.68 to 1.18)
Ethnic mixing<0.001<0.001
 Discordant11
 Concordant1.40 (1.21 to 1.61)1.33 (1.14 to 1.56)
Duration of the partnership in days*,§
 111
 (1 to 30)1.67 (1.40 to 2.00)0.90 (0.50 to 1.61)
 (1 to 60)1.70 (1.46 to 1.98)1.06 (0.69 to 1.61)
 (210 to 270)1.76 (1.48 to 2.09)1.38 (1.10 to 1.72)
Number of sex acts within a partnership in the preceding year<0.001<0.001
 1–411
 5–192.14 (1.78 to 2.57)1.78 (1.46 to 2.17)
 20–393.19 (2.18 to 4.66)2.65 (1.78 to 3.95)
 ≥403.95 (2.25 to 6.95)2.78 (1.55 to 4.99)
Anal sex2.53 (1.79 to 3.58)<0.0012.12 (1.48 to 3.05)<0.001
Sex-related drug use¶1.60 (1.40 to 1.86)<0.0011.56 (1.33 to 1.81)<0.001
Partnership is ongoing at the time of inclusion1.99 (1.59 to 2.49)<0.0011.42 (1.10 to 1.82)0.007
Concurrency of partnership**0.0690.027
 Definitely non-concurrent11
 Unknown0.81 (0.67 to 0.98)0.77 (0.64 to 0.94)
 Definitely concurrent0.89 (0.78 to 1.02)0.87 (0.75 to 1.02)
  • Missing data in duration, number of sex acts, anal sex, recreational drug use, ongoing partnership and concurrency of partnership were imputed.

  • *Continuous variables age in years, number of partners in the preceding 6 months, age difference in years and duration in days are modelled as restricted cubic splines with nodes on the 2.5th, 25th, 50th, 75th and 97.5th centiles; example ORs are given.

  • ‡Age of the partner subtracted from age of the participant.

  • §Only the month and year of first and last sexual contact were known, causing uncertainty in duration of the partnership.

  • ¶Recreational use of XTC (3,4-methyleendioxymethamfetamine), GHB (γ-hydroxybutyric acid), amphetamines, cocaine, poppers or sildefanil prior to or during sex.

  • **Only the month and year of first and last sexual contact of partnerships were known. For partnerships with an unknown concurrency status, concurrency could not be determined accurately.

  • aOR, adjusted OR.