Are Patients’ Ratings of Their Physicians Related to Health Outcomes?

INTRODUCTION

Observational studies examining relationships between patients’ perceptions of their physicians and patient-reported adherence, health status changes, and symptom resolution suggest that physicians’ interpersonal styles may influence patient outcomes.^1–9 Among these physician styles, greater patient-centeredness (manifested as engaging in a more participatory style, obtaining agreement on treatment, or supporting patient autonomy) has been associated with greater improvements in back pain, headache resolution, diabetes control, health status, compliance, and satisfaction. Unmeasured patient factors that might alter the reporting of physician style could confound interpretation of these studies, however. For example, certain patient personality characteristics have been associated with better perceived outcomes.^10–13 Because these characteristics might also be associated with more positive assessments of physicians, there may be a spurious association between physician styles and outcomes.

An alternative statistical approach to examining the relationship between physician styles and patient outcomes involves using multilevel modeling to test whether patient perceptions mediate the apparent physician effect on patient outcome. Multilevel modeling allows direct assessment of any physician contribution to patient outcome by analyzing how the physician variance component contributes to the total variance observed. One can then examine the extent to which physician effect (or variance component) is mediated by the patients’ ratings of the physician. A significant contribution of the physician variance component to the total variance associated with patient outcome, which is also mediated by the patients’ ratings of the physician, is a necessary condition for evidence of a relationship between physician style and patient outcome.

In this study, we studied the relationship between patients’ ratings of their physicians and reported changes in health status. Although controversial,^14–16 retrospectively reported health status change is considered a sensitive and valid measure of health outcomes.^17–19 We examined whether physician interpersonal style was associated with health status change, hypothesizing that a better perceived style would be associated with a smaller risk of health status decline. Mediation was assessed by first analyzing the physician’s contribution to the total variance while excluding patients’ perceptions. The analysis was then repeated including patients’ perceptions. The amount of observed reduction in the physician variance component is a measure of the extent of mediation resulting from patients’ perceptions.

METHODS

RESULTS

Analysis of MCO claims data showed that the sociodemographic, utilization, and clinical characteristics of MCO patients of enrolled physicians and physicians not enrolled were similar (Table 1⇓). Survey patients (Table 2⇓) were predominantly female and white, had some college education, and had at least a 5-year relationship with their primary care physician. A decline in health status during the previous year was reported by 1,051 (22.2%) patients.

There was a significant adjusted association between the composite measure of patients’ ratings of their physicians (STAK) and the risk of health status decline (adjusted odds ratio = 1.14; 95% confidence interval [CI], 1.05–1.24; P <.01). A 1-SD increase in the mean STAK score was associated with a 14% decreased risk of health status decline.

Multilevel analysis showed no evidence of a physician effect on reported health status decline. ρ, the proportion of total variance attributable to a physician effect, was 0.00 (95% CI, 0.00-0.00; P >.99). Because of concern about overadjustment, we repeated the analyses and excluded the Medical Outcomes Study Short Form-12 variables, with similar results.

We also repeated the health status change analysis, treating that variable as an interval-level 5-point scale in a random effects linear model. When we examined whether the absence of a significant effect in the dichotomous decline/no decline variable reflected insufficient statistical power, ρ was also 0.00 (95% CI, 0.00–0.05; P = .3). One standard deviation of the physician component or effect (4 SDs encompass approximately 95% of the total predicted physicians’ effect) was associated with a 0.03 step (95% CI, -0.03 to 0.10; P = .3) on the 5-step health status change scale. Note that 1 SD of the physician effect derives from the square root of the physician variance component.

We examined the physician variance component with STAK as a dependent variable. ρ was 0.10 (95% CI, 0.07–0.13; P <.01). One standard deviation of the physician effect was associated with a 0.30-SD change in STAK (95% CI, 0.25–0.35; P <.01).

DISCUSSION

Using methods similar to those of previous studies, we replicated previous research showing that patient ratings of their physicians are associated with patient-reported health outcomes.^1–9 With multilevel analysis, however, we found little evidence of a physician contribution to the risk of reported health status change. The absence of a significant physician effect (variance component) suggests there is little substantive association between perceived physician interpersonal style and patient outcome; the apparent relationship may reflect unmeasured patient confounding.

These findings have implications for understanding the relationships between physician behavior and patient outcomes. Previous research has linked patient-reported assessments of their care to patient-reported outcomes, including health status change, adherence, and satisfaction.^1–9 These studies have been used to conclude that a “better” physician style is related to improved outcomes. When patients provide both the physician assessment and outcome measures, however, caution is necessary, because the findings may be ascribed simply to shared method variance: patients who provide higher ratings of their physicians may also report better health. Our results suggest that although patient perceptions of physicians are related to reported health status changes, these effects may not be related to physician interpersonal styles.

Although we did not measure patient psychological factors, such factors may affect both patients’ ratings of their physicians and their reported health status changes. Patients who express negative affect also tend to report worse health and health care.^10–13 Self-efficacy may also influence adherence, health status, and physician ratings.^30,31 The potential confounding might also extend to biomedical outcomes, because these psychological factors have also been associated with glycohemoglobin,³² immune function,³³ and mortality.³⁴ Future studies in this field should adjust for these and other psychological characteristics.

We observed a significant physician effect (variance component) associated with STAK. This finding replicates earlier research suggesting that patient satisfaction is significantly clustered by physician.^20,35 This finding may reflect a physician effect on patient satisfaction, and this effect is possibly related to physician behaviors unconnected to reported health status changes. It is also plausible, however, that patients with differing levels of negative affect (or other characteristics) may be attracted to different physicians. Evidence also suggests that patients who are more optimistic and have high levels of self-efficacy are also more satisfied with their doctor-patient relationships³²; conversely, patients with more negative stereotypes of physicians also report lower satisfaction and adherence.³⁶ Careful research is necessary to tease out these alternatives, especially given the increasing use of patient satisfaction surveys to evaluate physicians.

Alternative approaches to assessing physician style may more robustly address some of the problems discussed here. Randomized trials to improve physician communication are less susceptible to confounding and reporting biases but are difficult to implement. Some, but not all, of these studies have shown only changes in communication and modest effects on patient satisfaction.^5,37,38 Studies using objective ratings of clinical encounters circumvent the biases described here, but they may be subject to other limitations; studies typically have linked physician behaviors with outcomes only for patients observed in the same encounters,³⁹ thus making it difficult to discern whether the observations are due to the effects of patients on physicians or vice versa. Observations on physician encounters with standardized patients may circumvent this problem.⁴⁰ All these approaches may be necessary to tease out the elements of physician communication style that contribute to optimal patient outcomes.

This study has a number of limitations. The cross-sectional design used retrospective assessments of health state changes (or transition states). As noted in the introduction, a modest literature, although controversial,^14–16 suggests that reported transition states are sensitive and valid measures of health outcomes.^17–19 Prospective assessments of changes in health status with time (before-and-after scores) are not without their own measurement problems.¹⁶ Thus, it is not clear that serial measurements of health status are the best and most bias-free way to address this question. It seems unlikely that a bias in our study would explain the essential findings: an association was observed with simple regression analyses similar to those used in previous studies, but that association disappeared on multilevel analysis.

There are several other notable study limitations. Although the claims data of study and comparison physicians were similar, physicians who agreed to participate in this study probably represent a selected, narrow spectrum of physician styles. The absence of observed physician effects remains consistent with a small effect that would require a larger sample size per physician to detect.^20,35 The narrow confidence intervals around the negative effect observed in this study, however, suggest that the power was adequate. We found, furthermore, a relationship between patients’ ratings of their physicians and the outcome to be comparable to effects reported in previous studies when we used methods similar to those in other studies.

Our study is the first to examine directly evidence for a physician contribution to the total variance observed. Our approach assumes a physician interpersonal style that is sufficiently consistent across patients to be measurable. This assumption also lies behind many published studies in the field, physician performance assessment, and much teaching about interpersonal communication. It is possible that interpersonal communication is entirely specific to particular patient-physician interactions, but, on average, physicians—at least those in this study—do not differ.

We conclude by quoting Francis Bacon: “For what a man had rather were true he more readily believes.” These results represent a cautionary tale: they suggest that apparent physician effects on care can be difficult to interpret. The uncritical assumption that all elements of a patient-centered physician interaction style (or, perhaps, styles that score well on measures of patient-centeredness) are always good for patients may impede the discovery and development of optimal ways of being with patients.⁴¹ Some studies suggesting the benefits of patient-centered care may reflect, in part, unmeasured patient confounding. Alternative study methods and analytic approaches, including multilevel analyses, will be necessary to tease out the components of physician behaviors that contribute to better patient outcomes.