Table 3.

Preferences for STI testing characteristics and demographic predictors of choosing to test derived using the (ASCL) model, expressed as ORs

Attributes and levels	ORs	CI	p Value
Time to appointment
Drop in the same day and wait	0.97	0.68 to 1.39	0.89
Within 24 h	0.91	0.73 to 1.15	0.44
Within 48 h	1.0	–	–
After 48 h but at the individual's convenience	1.04	0.83 to 1.30	0.72
Results waiting time
Same day	1.45	1.10 to 1.91	0.009
3 days	1.25	1.02 to 1.53	0.035
7 days	1.0	–	–
21 days	0.48	0.37 to 0.62	<0.001
Comprehensive of results
Positive results only	1.0	–	–
Positive and negative results	1.32	1.16 to 1.50	<0.001
Staff
Staff without specialist STI knowledge	1.0	–	–
Staff with specialist STI knowledge	2.05	1.78 to 2.37	<0.001
Comprehensiveness of testing
Tests for most STIs*	1.0	–	–
Tests for all STIs	4.06	3.36 to 4.90	<0.001
Results reporting method
Phone up test centre	1.0	–	–
Post to home address	0.64	0.52 to 0.79	<0.001
By email	1.07	0.84 to 1.35	0.60
Text or call to mobile phone by centre	1.20	0.98 to 1.48	0.07
Patient level characteristics
Choose test option A
Age	1.22	0.42 to 3.59	0.71
Sex	0.91	0.79 to 1.06	0.22
Previous STI test	1.32	0.41 to 4.25	0.64
Choose test option B
Age	1.03	0.36 to 2.96	0.96
Sex†	0.93	0.80 to 1.07	0.30
Previous STI test‡	1.35	0.43 to 4.22	0.60
Choose not to test	1.0	–	–

*Excluded tests were syphilis, herpes and HIV.

†Where male is the reference group.

‡Where not previously tested for a STI is the reference group.

For the main unadjusted model: log-likelihood   −977, number of observations  5256, number of groups (participants)  219, Wald χ² = 422 (p<0.001), McFadden's adjusted r² = 0.12, the model predicts 84% of answers correctly, an OR of 1 indicates the base alternative.

ASCL, alternative specific conditional logistic; STI, sexually transmitted infection.