Comparison of the disease activity score using the erythrocyte sedimentation rate and C-reactive protein levels in Koreans with rheumatoid arthritis

Chinese registry of rheumatoid arthritis: IV. Correlation and consistency of rheumatoid arthritis disease activity indices in China

Background:

Disease activity indices (DAIs) including disease activity score 28 (DAS28), simplified disease activity index (SDAI), and clinical disease activity index (CDAI) have been widely used in clinical practice and research studies of rheumatoid arthritis (RA). The objective of our study was to evaluate the correlation and concordance among different DAIs in Chinese patients with RA.

Methods:

A cross-sectional study, including patients enrolled in the Chinese registry of rheumatoid arthritis from November 2016 to August 2018, was conducted. The correlations were evaluated using Spearman correlation coefficient and concordance with Bland-Altman plots, quadratic weighted kappa, and discordance rates in the crosstab. For other indices, the optimal cutoff points corresponding to SDAI remission were explored through receiver operating characteristic curve analysis.

Results:

A total of 30,501 patients were included, of whom 80.46% were women. Most individuals were with moderate disease activity or high disease activity. High correlations among DAS28-erythrocyte sedimentation rate (ESR) and DAS28-C-reactive protein (CRP), SDAI and CDAI were observed. Similarly, the weighted kappa value among the indices was high. In Bland-Altman plots, a positive difference between DAS28-ESR and DAS28-CRP was observed, with an absolute difference of >1.2 in 3079 (10.09%) patients. In crosstab, approximately 30% of the patients were classified into different groups. Concordance values between SDAI remission and the optimal cutoff points of DAS28-ESR, DAS28-CRP, and CDAI were 3.06, 2.37, and 3.20, respectively.

Conclusions:

Although DAIs had high correlations and weighted kappa values, the discordance between DAIs was significant in Chinese patients with RA. The four DAIs are not interchangeable.

Serum progranulin level is associated with disease activity following orthopedic surgery in rheumatoid arthritis patients

Background

Few studies have focused on the ability of progranulin to predict postoperative disease activity in rheumatoid arthritis (RA) patients who have undergone surgery. This study evaluated serum progranulin levels in active RA patients and analyzed its relationship with postoperative disease activity.

Methods

One hundred thirty-two patients with active RA and 72 healthy subjects were included in this study. Serum progranulin was measured, and clinical data were collected. The postoperative 1-year Disease Activity Score in 28 joints calculated with C-reactive protein (DAS28-CRP) scores was evaluated as an indicator of disease activity. The predictive value of progranulin in postoperative 1-year disease activity in RA patients was also analyzed.

Results

Serum progranulin was significantly associated with the postoperative 1-year RA disease activity. The mean serum progranulin level in patients with a high disease activity was significantly higher than that of RA patients with low-to-moderate disease activity (54.2 ± 10.6 ng/mL vs. 46.7 ± 8.8 ng/mL). Serum progranulin was also evaluated as an independent predictive factor for postoperative 1-year RA disease activity in multivariate analysis (odds ratio [OR], 2.21; 95% confidence interval [CI], 1.02–8.85).

Conclusions

Serum progranulin levels may be a promising indicator of postoperative disease activity in RA patients who underwent orthopedic surgery.

DAS28-CRP Cutoffs for High Disease Activity and Remission Are Lower Than DAS28-ESR in Rheumatoid Arthritis

Objective

Guidelines do not specify how cutoffs for high disease activity differ between the Disease Activity Score 28‐joint count indices DAS28–erythrocyte sedimentation rate (ESR) and DAS28–C‐reactive protein (CRP). Studies that compare DAS28‐CRP and DAS28‐ESR depend on data from clinical trials, registries, or practices with multiple providers. Existing studies use data from patients who received immunosuppressive therapy. This study compared the DAS28‐ESR and DAS28‐CRP values from immunosuppressive treatment–naïve patients in a single physician practice.

Methods

A retrospective electronic medical chart review was conducted for new diagnoses of rheumatoid arthritis (RA; International Classification of Diseases [ICD]‐9 714), based on the American College of Rheumatology/European League against Rheumatology 2010 RA classification criteria. The number of patients with high disease activity (>5.1) was compared using ESR and CRP data to calculate the proportion of discordance. A receiver operator curve and Youden index was used to calculate the DAS28‐CRP high disease activity cutoff estimation that corresponds with DAS28‐ESR of more than 5.1.

Results

There were 171 patients included in this study. The baseline mean DAS28‐ESR was higher than the baseline mean DAS‐28 CRP: 5.1 ± 1.2 versus 4.1 ± 1.0 (P < 0.001); 48.5% of patients met criteria for high disease activity (score >5.1) compared with only 14.6% when measured by DAS28‐CRP. Discordance was 33.9%. κ coefficient was only .307. Receiver operator curve and Youden index analysis suggested that the cutoff point for high disease activity of DAS28‐CRP greater than 4.1, which corresponds to DAS28‐ESR greater than 5.1. Similarly, DAS28‐ESR posttreatment scores were significantly higher than DAS28‐CRP. When measured by DAS28‐ESR, patients in remission had higher scores as measured by DAS28‐ESR (1.81) than DAS28‐CRP (1.45).

Conclusion

There is a difference between DAS28‐ESR and DAS28‐CRP, even when calculated for immunosuppressive treatment–naïve patients. DAS28‐CRP is significantly lower than DAS28‐ESR.

DAS28-CRP and DAS28-ESR cut-offs for high disease activity in rheumatoid arthritis are not interchangeable

Background

In most patients with rheumatoid arthritis (RA), Disease Activity Score 28-joint count C reactive protein (DAS28-CRP) is lower than DAS28 erythrocyte sedimentation rate (DAS28-ESR), suggesting that use of the DAS28-ESR cut-off to assess high disease activity (HDA) with DAS28-CRP may underestimate the number of patients with HDA. We determined the DAS28-CRP value corresponding to the validated DAS28-ESR cut-off for HDA.

Methods

Baseline data were pooled from 2 clinical studies evaluating etanercept (ETN) plus methotrexate (MTX) or MTX in early RA; DAS28-CRP and DAS28-ESR were obtained, allowing the determination of the DAS28-CRP HDA value best corresponding to the DAS28-ESR cut-off of >5.1.

Results

At baseline, as expected, fewer patients had HDA by DAS28-CRP than DAS28-ESR; DAS28-CRP>5.1 and DAS28-ESR>5.1 had only modest agreement (κ coefficients 0.45–0.54). Mean DAS28-CRP and DAS28-ESR were 5.7 and 6.2, respectively, in the ETN+MTX group (n=571), and 6.0 and 6.5 in the MTX group (n=262). A DAS28-CRP cut-off of 4.6 corresponded to a DAS28-ESR cut-off of 5.1.

Conclusions

We have shown that a DAS28-CRP of 4.6 corresponds to 5.1 for DAS28-ESR. Since this is substantially lower than the DAS28-ESR cut-off of 5.1, using 5.1 as the cut-off for DAS28-CRP underestimates disease activity in RA.

Trial registration number

NCT00195494; NCT00913458.