The predictability of individual primary care costs and its impact on managed care plans.
In the context of reorganizing the delivery of primary care, a better understanding of the evolution of family practice costs would be useful for those managing the health care system. This study examined the level of use and transition probabilities of remaining a low user of physician care in family practices over 5 years among a population with no restriction of age or functional status. The entire population (n = 285, 305) of one administrative area of the Province of Quebec (Canada) was followed from 1996 to 2000 and classified for each year into seven cost categories according to individual costs of care in family practices. The Pr of staying in the same category or moving to another one has been examined and these transitions were calculated for 2, 3, 4 and 5 year-periods. Recourse to care was very stable over time. The Pr of staying in the same cost category or moving to the adjacent one was always 91% between 2 years and still as high as 86% between 4 years. Less than 5% of the population jumped over more than two categories. More than three quarters of the population never exceeded Candollar 200 over the 5 years while only 2.5% had a chance to reach Candollar 500. Costs of care in family practices were highly correlated with visits (r = 0.94), suggesting the role of chronicity as a determinant of expenditures in these settings. The stability of individual costs of care in family practices illustrated by the high transition probabilities over time indicates the possibility to forecast these costs in a perspective of capitation payment plans.