This study aimed to analyze whether the interaction between patients and their doctors, as measured by their disagreement on information and advice given during the consultation, varied according to the patient's body mass index.

Twenty-seven general practitioners and 585 patients from three regions in France participated in the quantitative phase of the project in September and October of 2007 and answered questionnaires collecting both general practitioners' and patients' perceptions of information and advice given at the end of the consultation.

Researchers here explored differences concerning the patient's and doctor's declarations about actions, information, and advice during the same visit, the patient's health status, and the perceived quality of their relationship. For example, the questions about weight loss were: "Did your doctor advise you to lose weight during the consultation?" (Answered by patients) and its mirror "Did you advise this patient to lose weight during the consultation?" (Answered by doctors). Differences in answers given by doctors and their patients were used to define disagreement.

Agreement between patients and doctors was weak (20 to 40 per cent agreement) or moderate (40 to 60 per cent agreement) for most of the questions, including questions about actions, information, advice, and patient's health status discussed during the doctor's appointment. The agreement was very weak (less than 20 per cent agreement) for questions about the perceived quality of the patient-doctor relationship.

Researchers also found that there was more doctor-patient disagreement the more overweight the patient was. Disagreement was particularly pronounced for advice given by doctors on weight and lifestyle issues. Compared to patients with a "normal" BMI, overweight patients were more likely to disagree with their doctors regarding advice given on weight loss, advice given on doing more physical activity, and advice about nutrition.

"An exploration of the patient's representations and difficulties related to weight could be offered by the general practitioners as a basis for discussion and appropriate support," said the study's lead author, Laetitia Gimenez.