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. Author manuscript; available in PMC: 2008 Nov 1.
Published in final edited form as: Ann Epidemiol. 2007 Aug 6;17(11):854–862. doi: 10.1016/j.annepidem.2007.05.014

Table 3.

Risk factors for acquiring Group B Streptococcus by capsular type. Logistic regression model predicting incidence of a capsular type or capsular type grouping, using all other data as reference. 129 female and 128 male freshmen college students living in a single dormitory.

Risk factor Beta Std Error OR (95% CI) P value
Capsular type la or lb
Log frequency of sex acts* 0.172 0.220 1.2 (0.77,1.83) 0.43
Number of sex partners previous year 0.079 0.149 1.1 (0.81,1.45) 0.59
Eats fish 2 or more times per week 1.982 0.489 7.3 (2.78,18.90) <0.001
Frequency eats in the dormitory −0.220 0.277 0.80 (0.47,1.38) 0.43
Male gender −0.100 0.509 0.90 (0.33,2.45) 0.84
Capsular type V
Log frequency of sex acts* 0.560 0.198 1.8 (1.19,2.58) 0.001
Number of sex partners previous year −0.244 0.202 0.8 (0.53,1.16) 0.23
Eats fish 2 or more times per week 0.538 0.659 1.7 (0.47,6.23) 0.41
Frequency eats in the dormitory 0.786 0.520 2.2 (0.79,6.07) 0.13
Male gender −0.313 0.495 0.73 (0.38,1.93) 0.53
All other capsular types
Log frequency of sex acts* 0.362 0.184 1.4 (1.00,2.06) 0.05
Number of sex partners previous year 0.328 0.117 1.4 (1.1,1.75) 0.005
Eats fish 2 or more times per week −0.134 0.786 0.88 (0.19,4.08) 0.87
Frequency eats in the dormitory −0.504 0.253 0.6 (0.37,0.99) 0.05
Male gender −0.024 0.508 0.9 (0.36,2.64) 0.96
All capsular types, combined
Log frequency of sex acts* 0.383 0.119 1.5 (1.16,1.85) 0.001
Number of sex partners previous year 0.142 0.082 1.2 (0.98,1.36) 0.08
Eats fish 2 or more times per week 1.113 0.354 3.0 (1.51,6.10) 0.002
Frequency eats in the dormitory −0.136 0.183 0.9 (0.61,1.25) 0.46
Male gender −0.085 0.301 0.9 (0.51,1.66) 0.78

Risk periods calculated assuming no infection with multiple capsular types, so is a slight under-estimate

*

Log base 2 of maximum (frequency oral sex, vaginal sex), interpreted as the ratio of the odds of GBS incidence for a doubling in the number of sex acts. For example, an OR of 1.7 is interpreted as a 70% increase in odds of GBS with a doubling in the number of sex acts.