Rate of Case Reporting, Physician Compliance, and Practice Volume in a Practice-Based Research Network Study

MINITAB was used for statistical analyses. Descriptive statistics were calculated for the outcome variables. Because data for reported rate of dyspepsia visits and compliance were not normally distributed, Spearman rank correlation (“ = 0.05) was used to test the hypotheses that practice volume, protocol compliance, and reported rate of dyspepsia visits were correlated. The one solo practitioner was placed with the group practice physicians because of a high level of similarity in all outcome variables. Because differences were noted among the practice types, the Kruskal-Wallis test was used to assess differences in patient volume, compliance, and reported rate of dyspepsia visits.

Results

The average participant in this study was a 46-year-old male physician who had been in practice for 17 years and saw 61.5 patients per week Table w1. Eight physicians were located in group practices, while 5 were in multispecialty and 3 were in academic practices. The mean reported rate of dyspepsia visits was 7.7 cases per 1000 patient visits. Initial dyspepsia visits accounted for 118 of the 231 reported visits for dyspepsia (0.51%), with a total of 45,337 patient visits recorded by participating physicians.

The average participant recorded visits over 43.2 weeks of the possible 53-week study (81.5% overall participation rate). The average self-reported compliance with the study protocol was 6.7 on a 10-point scale but with a very wide range (from 1 to 10). Significant differences among practice types were found in patient volume, reported rate of dyspepsia visits, and self-reported compliance Table 2. Participants from group practices had the highest patient volumes but the lowest rate of dyspepsia visits and compliance. Academic physicians saw the least number of patients but had the highest reported rate of dyspepsia visits and compliance.

Significant negative rank correlations were found to exist between patient volume and reported rate of dyspepsia visits (Figure 1: rs = -0.548; P .05) and between patient volume and compliance with protocol (Figure 2: rs = -0.490; P .05). A significant positive rank correlation was found between compliance with protocol and rate of dyspepsia visits (Figure 3 (: rs = 0.551; P .05). No significant correlation existed between the number of weeks of participation and patient volume (rs = -0.303), rate of dyspepsia visits (rs = 0.065), or compliance with protocol (rs = 0.415).

Discussion

Practice volume can have a significant effect on physicians’ reporting rates in practice-based studies. The rate of dyspepsia visits, as measured by the identification of patients meeting study criteria and having a completed data form, was negatively related to the number of patients seen per week by the physician. Practice volume appears to be linked to reporting by way of compliance. As an extension, it appears that physicians are generally accurate in self-assessment of their compliance with a protocol.

Although previous evaluations of PBRNs have demonstrated high levels of accuracy within reported data,¹⁰ the results reported here are somewhat disturbing. If other studies show similar results, the idea that PBRNs can assess prevalence of medical conditions could be called into question. Also, there may be a bias in the higher? volume practices for patients with more severe symptoms to be reported in preference to those with less “attention getting” symptoms, or in low-volume practices to seek out problems for which the patient did not seek attention. Consequently, even when a medical problem is identified, there may be patient selection bias toward those with more or less severe symptoms.

Additional burden and lack of practice support were common reasons for withdrawing from participation in PBRNs.¹¹ Overall participation and compliance with a research protocol, therefore, is likely related to the complexity of that protocol. While the reported rate of dyspepsia visits was negatively related to practice volume, the simple reporting of a weekly tally of patients seen in clinic was not. Consequently, compliance-sensitive measurements (eg, prevalence) may need simple time-efficient protocols. For example, full compliance with the protocol for the approximately 1050 physicians currently involved in the Centers for Disease Control and Prevention US Influenza Sentinel Physician Surveillance Network requires less than 3 minutes per week. This surveillance network for monitoring prevalence of influenza-like illness is a highly accurate, timely, and valued component of influenza surveillance.¹² Other enhancements for study protocols may include decreased periods for data gathering, use of intermittent reporting, and use of other office staff for case identification.

Limitations

This study is limited by a potential lack of generalizability. It is an observational study of physician behavior around a complex and relatively high-burden data collection instrument. There were no true standards regarding prevalence of dyspepsia at any location, thus allowing for the possibility that patient populations differed significantly among sites. Self-reported compliance with the research protocol was based on recall 4 months after the end of the data collection period. Also, some of the effect attributable to patient volume could alternatively result from the types of physicians involved in this study.