Table 2 GP questionnaire. Description of scales and items. (Original items are in Dutch*)

I am very satisfied about the functioning and the structure of the GP cooperative (+)

I am pleased with the current GP cooperative (+)

I am very satisfied with the current organisation of out-of-hours primary care (+)

Scale 2. Current out-of-hours care is better organised than formerly (Cronbach's α = 0.92; mean (SD) = 89.8 (19.5))

Out-of-hours care was better organised before the establishment of GP cooperatives (+)

I prefer the former organisation of out-of-hours primary care (-)

The current organisation of out-of-hours care is not an improvement compared to the former organisation (-)

BLOCK 2. Perceptions and subjective evaluations on working conditions in the present organisation

Scale 3. Experienced a high workload (Cronbach's α = 0.87; mean (SD) = 65.5 (18.4))

The workload at the GP cooperative is too high (+)

Out-of-hours care during daytime on Saturday and Sunday is very aggravating (+)

Usually, out-of-hours service is much too aggravating (+)

I do not experience such a high workload at the GP cooperative (-)

Performing out-of-hours care is absolutely not aggravating (-)

Out-of-hours care during daytime in the weekends is not too high (-)

Scale 4. One feels safe at the cooperative (Cronbach's α = 0.87; mean (SD) = 76.9 (18.7))

Sometimes, I feel unsafe at the GP cooperative during out-of-hours (-)

During my shifts at the GP cooperative, I never feel unsafe (+)

Regularly, I feel unsafe at the GP cooperative during out-of-hours (-)

Scale 5. One feels safe during home visits (Cronbach's α = 0.84; mean (SD) = 76.0 (18.4))

Regularly, I feel unsafe when performing home visits during out-of-hours (-)

Sometimes, I feel unsafe when performing home visits during out-of-hours (-)

Usually, I feel safe when performing home visits during out-of-hours (+)

BLOCK 3. Opinions and beliefs on professional philosophy

Scale 6. Out-of-hours care is an essential part of primary care (Cronbach's α = 0.97; mean (SD) = 60.3 (31.7))

These days, out-of-hours care should no longer be an essential part of primary care (-)

Out-of-hours care is definitely an essential part of primary care (+)

Out-of-hours care should always be a part of general practice (+)

There is no place anymore for out-of-hours care in general practice (-)

Scale 7. Anonymity of care is a problem (Cronbach's α = 0.90; mean (SD) = 32.9 (21.8))

Because the GP of the cooperative and the patient are not familiar with each other, there is a risk for inadequate treatment (+)

Because of anonymity of care there is a risk that diagnostics and treatment are not adequately adjusted for the patient's needs (+)

One of the big disadvantages of the GP cooperative is the anonymity of care, because the GP is not familiar with the patient (+)

Because the GP of the cooperative and the patient are not familiar with each other, there is a risk for inadequacy of care (+)

Scale 8. Gatekeeper function is well guaranteed (Cronbach's α = 0.74; mean (SD) = 64.5 (16.8))

I think the GP gatekeeper function at the GP cooperative is well guaranteed (+)

I am afraid that the GP gatekeeper function during out-of-hours will disappear (-)

I believe that in the near future the GP gatekeeper function will be put under too much pressure (-)

I think the GP gatekeeper function at the GP cooperative is well protected (+)

Scale 9. Availability of patient dossiers is important (Cronbach's α = 0.93; mean (SD) = 57.4 (24.1))

As far as I am concerned, I do not need the availability of my colleagues' patient dossiers (-)

I think it is a serious problem that my colleagues' patient dossiers are not at my disposal (+)

The availability of patient dossiers of the other participating GPs during out-of-hours is absolutely unnecessary (-)

During out-of-hours I am hindered in my practice, because of lack of information about my colleagues' patients (+)

BLOCK 4. Evaluation of the cooperation with medical specialists at the local hospital

Scale 10. Cooperation with medical specialists is good (Cronbach's α = 0.94; mean (SD) = 62.7 (23.0))

Sometimes, the cooperation between GPs and medical specialists is not so good (-)

I think that during out-of-hours the understanding between GPs and medical specialists is sometimes pretty bad (-)

I think that during out-of-hours the cooperation between GPs and medical specialists is always fine (+)

Generally, the cooperation between myself and the medical specialists of the hospital is good (+)