Cross-sectional and longitudinal analyses of nutrition guidance by primary care physicians.

OBJECTIVE

To investigate in primary care physicians (PCPs) the determinants of a nutrition guidance practice ('noticing patients' overweight and guidance of treatment'), as well as their mechanism of action, in a cross-sectional and a longitudinal approach.

DESIGN

Mixed longitudinal design. Five years follow up study of a previous cross-sectional study in October 1992.

SUBJECTS

A representative sample of 675 Dutch PCPs, in practice for 5 up to 20y.

INTERVENTIONS

A shortened version of the Wageningen PCPs Nutritional Practices Questionnaire was mailed to the subjects in August 1997.

MAIN OUTCOME MEASURE

To obtain with the LISREL-program a model of the mechanism of action of determinants of the dependent variable 'noticing patients' overweight and guidance of treatment' with an adequate fit of the empirical data, both in the cross-sectional and in the longitudinal approach.

RESULTS

The same set of predisposing factors and intermediary factors explains the dependent variable both in two different representative cross-sectional study populations of PCPs, and in a cohort cross-sectional study at two points in time. Two dynamic LISREL-models were developed (the 'determinant-longitudinal approach' and the 'early behaviour longitudinal approach') which explain the dependent variable. The latter model has, as added value, a gain in explained variance. In 5 y time, the dependent variable decreased significantly (P < 0.001).

CONCLUSIONS

This study reconfirms that PCPs' nutritional guidance practices are determined partly directly by predisposing factors, and indirectly via driving forces and barriers. However this study also reveals that an important nutrition guidance practice of PCPs, 'noticing patients' overweight and guidance of treatment', shows a significant decrease over the last 5 y. At the same time, two of the four predisposing factors and two of the three driving factors also decreased significantly. As research findings indicate that the role of diet in health and disease becomes of greater influence PCPs need to be activated to apply their responsibility in this field within a multi-faceted approach.