How healthcare is organized may affect how well blood pressure is controlled

The study shows that high blood pressure (BP) is less likely to normalize during times when the number of unique doctors on staff is higher and more patients are seen, suggesting that "[W]hen practices are busier, BP care may suffer," writes Nancy R. Kressin, PhD, of Boston University School of Medicine, and the VA Boston Healthcare System and her colleagues. They add, "Our findings suggest that clinical operations factors can affect clinical outcomes like BP normalization, and point to the importance of considering outcome effects when organizing clinical care."

Staffing Levels and Appointment Volume Affect BP Control

Using data from the electronic medical records system of a large, multi-clinic internal medicine practice, Dr. Kressin and colleagues looked at how organizational factors affected time to bring high blood pressure under control. The study focused on approximately 7,400 patients who had episodes of uncontrolled BP requiring treatment.

The researchers organized the follow-up data into more than 50,000 "person-months" and assessed the time needed for BP to normalize. On average, it took five months to achieve normal blood pressure.

The study focused on four specific organizational factors affecting healthcare access and continuity of care: the volume of patient appointments, both for the entire practice and for individual clinicians; the amount of primary care practitioner (PCP) staffing, that is, physicians and nurse-practitioners; and the number of different PCPs.

The results showed that blood pressure was less likely to normalize during months with a higher number of unique PCPs (independent of the number of PCP full-time equivalents). From the highest to the lowest numbers of unique PCPs, the probability of BP normalization was reduced by nine percentage points.

In addition, normal BP was less likely to be achieved in months with a higher volume of practice appointments. From the highest to the lowest volume of appointments, the likelihood of BP normalization decreased by six percentage points.

Neither the appointment volume of individual clinicians nor the practice total clinician full-time equivalent staffing levels affected the probability of normalizing BP levels. The study accounted for the fact that BP can only be measured at times when patients make a clinic visit. Certain patient factors were also associated with lower rates of BP normalization, including older age and lower kidney function.

Uncontrolled BP control is a common problem, and rates of BP control are increasingly used as an indicator of healthcare quality. Dr. Kressin and colleagues applied economic productivity models to try to understand the organizational factors that might influence BP care and outcomes.

So why was BP less likely to normalize when there were more PCPs and more appointments available? "It may be that the higher the clinic practice volume gets, the more compromised care may become, because clinical and administrative staff become busier and more pressured to move greater numbers of patients through limited space in the system," Dr. Kressin suggests. "Ultimately, the less likely clinicians are to be able to devote time and attention to help patients normalize their uncontrolled blood pressure."

For example, the common practice of augmenting clinic staff by hiring additional part-time providers may "erode care continuity"--and thus adversely affect patient care. Dr. Kressin and coauthors conclude, "[H]ealth care organizations should be wary of increasing practice-level appointment volume without also adjusting administrative and clinical capacity."