Visit frequency for essential hypertension: observed associations.

Data from the British Department of Health and Social Services Hypertension Care Computing Project were analyzed to study determinants of visit frequency in hypertension management. The 457 patients from five general practices made 7974 visits between 1971 and 1985 resulting in 7391 intervals on which evaluation could be based. The mean interval between visits was 113 days (SD = 110 days) with a median interval of 91 days. Visit interval was influenced by level of blood pressure and length of time in follow-up. For diastolic pressures less than 104 mmHg the mean visit interval was 4 months, contrasting with 2 months for diastolic pressures greater than 130 mmHg. Visit intervals became longer with increasing length of time in follow-up, independent of level of blood pressure. Shorter intervals reflected initial management and getting the blood pressure reduced; longer intervals may reflect patients' failure to keep scheduled appointments. Between practices, mean visit intervals ranged from 99 to 193 days (median 72 to 164 days). These differences were reduced after adjustment for length of time the patients had been in follow-up. Patient age, sex, body mass index, and the presence of angina pectoris were not associated with visit interval. The analyses illustrate how process and outcome may be linked in ambulatory care practice as a means of determining rational guidelines for optimal utilization of health services.