Table 1.

Description of study measures

	Description of items and scales	Scoring, and interpretation of scores:
Patient and clinical characteristics	NCR: age at time of questionnaire, primary treatment, time since diagnosis, and tumor stage (TNM classification). Patient reported: education level, marital status, comorbidity using the self-administered comorbidity questionnaire [19].	Educational level: low (no education and (lower) primary education), intermediate (secondary (vocational) education), and high (higher (vocational) education and university)
Involvement of GP
GP contact	Assessed with one question: ‘Did you have contact with your GP in the period you were recovering from your cancer treatment?’	Yes/no/I don’t know
Preferring more GP contact	Assessed with one question: ‘Would you like to have had (more) contact with your GP during the follow-up phase?’	Yes/no
Symptoms	Patient reported, using the EORTC QLQ PR-25 [20]: urinary symptoms, incontinence aid, bowel symptoms, hormonal symptoms, sexual activity, sexual functioning.	0-100: higher scores implies more symptoms or worse functioning
Patients’ evaluation of their GP
Satisfaction with GP	Item: Assessed using a self-developed question: ‘Are (were) you satisfied with your GP in the phase after treatment?’. Scale: The item was linearly transformed into a scale.	Item: Five-point response format ranging from ‘very satisfied’ to ‘very unsatisfied’. Scale: 0-100: higher scores implied more satisfaction with GP
Trust in GP	Items: Assessed using two self-developed statements: ‘I have a lot of trust in my GP’ and ‘I trust my GP in referring me to the hospital, when necessary’. Scale: The items were combined into one scale (Cronbach’s α = 0.84).	Items: Five-point response format ranging from ‘totally agree’ to ‘totally disagree’. Scale: 0-100: higher scores implied more trust in GP
Appraised knowledge of GP	Items: Assessed using three self-developed statements: ‘I think my GP has sufficient knowledge of the side effects and consequences of the cancer treatments’, ‘I think my GP has sufficient knowledge to decide whether it is necessary to refer me to the hospital for my complaints’, and ‘I think my GP knows which medical specialists are experts in assisting people with cancer’. Scale: The items were combined into one scale (Cronbach’s α = 0.75).	Items: Five-point response format ranging from ‘totally agree’ to ‘totally disagree’. Scale: 0-100: higher scores implied higher knowledge rating of GP

Abbreviations. NCR Netherlands Cancer Registry, NA Not Applicable, GP General Practitioner, EORTC QLQ PR-25 European Organization for Research and Treatment of Cancer Quality of Life Questionnaire – Prostate Cancer Module