In this study, we found evidence for clinically meaningful differences between patient and physician assessments of RA disease activity in 36% of cases. Physician assessments under scored patients’ assessments in the overwhelming majority (85%) of discordant pairs. The presence of greater depressive symptoms was an independent predictor, while a higher swollen joint count was associated with lower odds of discordance. These findings were robust across different cut-points for discordance. As the threshold of discordance was lowered, however, we found that worse functional status and non-English language were independently associated with discordance. An exploration of our findings revealed that mean patient global assessments increased with higher depressive symptoms while mean physician global scores remained similar. In contrast, the mean patient and physician global assessments were least discordant at the highest tertile of swollen joint counts. Among subjects with positive discordance (patient scores worse than physician), mean DAS 28 scores calculated with and without the patient global were most divergent. This important finding suggests that among patients who are discordant with their physicians, the DAS 28 score may not accurately reflect disease activity.
Discrepancies between patient and professional assessments of pain, function, and overall health have been reported in RA (5
). Nicolau et al. evaluated differences in ratings of disease activity using a 3 cm cutoff on a 10 cm VAS and found a difference in 37%, an effect nearly identical to that in our study (5
). Suarez-Almazor, et al. explored discordance in ratings of health status, and reported, as in our study, physicians on average rated their patients’ health as better than did patients. The impact of language or psychological well-being on discordance was not reported (6
). Our finding of Chinese language being associated with decreased odds of discordance may be a statistical artifact, or perhaps related to the quality of the Chinese language interpreter in our clinics.
The impact of depression on symptom reporting in RA has been well-documented (28
). Zautra et al. found an association between recurrent bouts of major depression and increased risk for pain (29
). While depression has been shown to be associated with more pain and worse function (30
), there is no literature in RA that explores the role of depression and its association with discordance. Depression has been associated with symptom underestimation by physicians in non-rheumatic diseases (17
). In one study of adult diabetics screened for depression, Swenson et al found that patients with severe depressive symptoms were more likely to report suboptimal clinician-patient communication (18
). The authors hypothesized that this could be due to competing demands, unmet expectations, or poor concentration related to depression. It is possible that the association between depressive symptoms and discordance observed in our study is a result of poor communication for any of the aforementioned reasons. Given the prevalence of co-morbid depression and RA (31
), the mechanisms for how depressive symptoms are associated with discordance warrants further investigation.
Finally, and perhaps most notably, no study has evaluated the effect of discordance on the DAS 28. In our study, the largest mean difference between the DAS 28 4-variable and the DAS 28 3-variable (calculation without the patient global) was seen in patients with positive discordance. One explanation may be related to an association of depressive symptoms and discordance. Higher disease activity as measured by the DAS 28 may reflect both a patient’s mood as well as disease activity. Ward found that self-report of pain and global disease severity may be confounded by depression (32
). Our analysis indicates that depressive symptoms are associated with positive discordance, which, in turn, may impact the DAS 28. If this is in fact true, rheumatologists (as guided by ACR recommendations to aim for low disease activity) may escalate therapy for patients whose apparent moderate or high disease activity as reflected by the DAS 28 is influenced more by depressed mood than by systemic inflammation, joint pain or swelling. In such cases, appropriate recognition and treatment of depressive symptoms may be warranted. Alternatively, depressive symptoms may be an emotional manifestation of the systemic, inflammatory process common in RA and depressed mood may, in part, be driven by heightened levels of pro-inflammatory cytokines postulated in the literature (33
A third explanation may be that depression somehow interferes with the efficacy of therapy in RA and blunts the response as measured through the components of the DAS 28. A recent study by Hider and colleagues to investigate the prevalence of depression among RA patients initiating anti-TNF therapy reported a high prevalence of depression (47.5%) as well as a higher mean DAS 28 among depressed patients at baseline prior to treatment, and at 3 and 12 months while on therapy (34
). Depressed patients had a poorer response to anti-TNF therapy with smaller reductions in all
components of the DAS 28 when compared to non-depressed patients at 3 months. This study has several limitations. First, our study population was largely non-White (83%), non-U.S. born (78%), and from an urban area. While this may limit the generalizability of our findings, it could also be viewed as a strength insofar as vulnerable populations have been shown to be at greater risk of miscommunication with physicians, experience lower quality of care, and less commonly participate in research studies (35
). Second, we measured depressive symptoms using the PHQ-9 rather than the gold standard of a clinical diagnostic interview. The PHQ-9, however, has been shown to be a reliable and valid screening measure of depression severity in the outpatient setting (21
). Third, this was a cross-sectional study and, as such, a causal relationship between depressive symptoms and discordance cannot firmly be established; nor can we assess whether discordance lessens over time. Fourth, there are no established cut-points for what constitutes “significant” discordance in the literature, but it should be noted that 25 mm exceeds a half standard deviation of discordance (26mm) which approximates a minimal clinically important difference (26
). In addition, we performed sensitivity analyses which supported our findings. As we accrue longitudinal data and perform additional analyses, we will examine in greater depth the relationship between depressive symptoms and discordance. Finally, there were no direct observations of patient-physician communication during clinic visits or a measure of quality of the doctor-patient relationship which could have provided additional insights as to contributors of discordance. Potential next steps in better understanding why discordance exists could include a qualitative study to explore how beliefs and/or culture may influence the reporting of disease severity by both patients and physicians and, an evaluation of the role of health literacy as a potential predictor of discordance.
In conclusion, we found that 36% of RA patients differed from their physicians to a clinically meaningful degree with physicians systematically under-scoring disease severity relative to patients’ self-assessments. Depressive symptoms were common, with 30% of subjects exceeding a cut-point of major depression. Independent predictors of discordance included greater depressive symptoms and a lower swollen joint count. In sensitivity analyses, we also found that non-English language and functional status were associated with discordance.
Future studies should prospectively evaluate the impact of discordance in disease activity assessment in RA and on the DAS 28 in particular, and assess the contribution of depressive symptoms to the quality of clinician-patient communication. In addition, reducing discordance may be an important goal in and of itself, as it has been shown that when doctors and patients agree, adherence and outcomes improve (3
). Further investigation of the relationships between mood, disease activity, and discordance may help guide interventions to improve care for adults with RA.