Table 6.

Adjusted associations between participation in the extended hours access scheme and patient experience, using multilevel random-effects regression models, propensity score matching and instrumental variable analysis

	Satisfaction with opening hours	Experience of making an appointment	Overall experience
Number of responses	731 700	725 885	753 020
Number of general practices	7399	7399	7399
Between-practice SD*	4.5	7.0	4.3
Random-effects regression models
Mean difference (95% CI)	1.25 (0.96 to 1.55)	0.48 (0.07 to 0.90)	0.32 (0.04 to 0.60)
p Value	<0.001	0.022	0.026
Standardised mean difference	0.28	0.07	0.07
Propensity score matching
Mean difference (95% CI)	1.35 (1.00 to 1.70)	0.51 (−0.03 to 1.04)	0.39 (0.03 to 0.74)
p Value	<0.001	0.063	0.032
Standardised mean difference	0.30	0.07	0.09
Instrumental variable analysis
Mean difference (95% CI)	1.36 (0.71 to 2.00)	1.79 (0.84 to 2.75)	1.13 (0.50 to 1.76)
p Value	<0.001	<0.001	<0.001
Standardised mean difference	0.30	0.25	0.26

Numbers of responses and general practices correspond to respondents with no missing data for relevant outcome models.

Mean differences are relative to the means for general practices not participating in the scheme.

All models adjusted for/balanced: respondent age, gender, ethnicity, socio-economic status, ability to take time off work to see a GP, confidence in managing health; and general practice registered population size, number of full-time-equivalent GPs per 10 000 patients, socio-economic status of registered population, Quality and Outcomes Framework achievement, urban/rural location and region of England.

*SD of practice-level random effects adjusted for patient characteristics only. Standardised mean differences equal mean differences divided by this SD.