Validation of serostatus of rheumatoid arthritis using ICD-10 codes in administrative claims data

Economic and Humanistic Burden of Rheumatoid Arthritis: Results From the US National Survey Data 2018-2020

OBJECTIVE

Our objective was to estimate the economic and humanistic burden among US adults with rheumatoid arthritis (RA).

METHODS

This study analyzed results from the Medical Expenditure Panel Survey from 2018 to 2020. Adults (aged ≥18 years) self-reporting with RA or with the presence of the International Classification of Disease, 10th Revision clinical modification codes were identified. Healthcare expenditures (inpatient care, outpatient care, emergency department, office visits, prescription medications, home health, and others) were measured. The Short Form 12 Health Survey physical component summary (PCS), mental component summary (MCS), activities of daily living (ADL), and instrumental ADL (IADL) were measured. Two-part models assessed the incremental increase in the health care expenditures for the RA group compared to the non-RA group. In addition, the multivariable linear regression was used to evaluate the marginal difference in PCS and MCS between those with RA and those without RA, whereas the multivariable logistic regression models were used to evaluate the association between ADL and IADL by RA status.

RESULTS

Annually, 4.27 million adults with RA were identified. The two-part model showed significantly higher total annual healthcare expenditures in the RA group than non-RA group (mean $3,382.971 [95% confidence interval (CI) $1,816.50-$4,949.44]). Compared to the non-RA group, the RA group was associated with lower PCS scores (mean 4.78 [95% CI 3.47-6.09]) and similarly lower MCS scores (mean -0.84 [95% CI -2.18 to 0.50]), as well as increased odds of requesting ADL (adjusted odds ratio [aOR] 2.02 [95% CI 1.59-2.56]) and IADL assistance (aOR 2.11 [95% CI 1.57-2.84]).

CONCLUSION

RA was associated with higher health care expenditures, particularly prescription medication costs, and was associated with suboptimal quality of life.

Does Rheumatoid Arthritis Increase the Risk of COPD?: A Nationwide Retrospective Cohort Study

BACKGROUND

Most reports of pulmonary manifestations in rheumatoid arthritis (RA) have been related to interstitial lung diseases. RA and COPD are both chronic inflammatory systemic diseases.

RESEARCH QUESTION

Does RA increase the risk of developing COPD? Is there a difference between seropositive and seronegative RA in the risk of COPD?

STUDY DESIGN AND METHODS

Using the Korean National Health Insurance Database, we screened individuals diagnosed with RA between 2010 and 2017. We identified 46,030 patients with RA (32,608 with seropositive RA and 13,422 with seronegative RA) and 230,150 matched control individuals; we monitored them until December 2019. We used multivariate Cox proportional hazard models to estimate the adjusted hazard ratio (aHR) of risk factors for the development of COPD.

RESULTS

The incidence of COPD among patients with RA was 5.04 per 1,000 person-years; it was 2.23 per 1,000 person-years in the control group. Patients with RA showed a higher risk of developing COPD (aHR, 2.11; 95% CI, 1.96-2.28) compared with the control group. Although both seropositive RA and seronegative RA were associated with an increased risk of COPD, patients with seropositive RA had a higher risk for the development of COPD (aHR, 1.26; 95% CI, 1.09-1.46) than patients with seronegative RA. In the subgroup analyses, smoking history did not demonstrate significant interactions between RA and COPD development.

INTERPRETATION

RA was shown to be associated with an increased risk of COPD development, augmented by seropositivity. Physicians should monitor respiratory symptoms and pulmonary function carefully in patients with RA.

Validation of diagnosis algorithms for ankylosing spondylitis in claim-based database

BACKGROUND

Claims-based algorithms using International Classification of Diseases (ICD) codes have become a common approach for researchers to define ankylosing spondylitis (AS) in studies. To address potential misclassification bias caused by the claim-based algorithms, we conducted the current study to validate whether these algorithms of medical claims could accurately represent AS diagnoses.

METHODS

Patients diagnosed with AS based on ICD codes were retrieved from the electronic medical records database at a Taiwanese medical center (Chung Shan University Hospital, Taiwan). After random sampling and stratification based on age and sex, the medical information of participants was appraised based on the 2009 ASAS guideline to evaluate the actual status of ICD codes claim-based AS patients. Positive predict values (PPV) of different algorithms of ICD codes were also calculated.

RESULTS

Within the 4160 patients with claim-based AS diagnosis, 387 eligible patients were finally included in the study design after random sampling. The PPV of the diagnostic algorithm of having at least 4 outpatient or 1 inpatient ICD record was 72.77 (95% CI, 66.79-78.75), whereas the PPV increased to 85.64 when the diagnoses were restricted to be made by rheumatologists (95% CI, 80.53-90.74).

CONCLUSIONS

While performing database studies, researchers should be aware of the low PPV of specific algorithms when defining AS. Algorithms with higher PPV were recommended to be adopted to avoid misclassification biases.

Real-World Treatment Effectiveness of Disease-Modifying Antirheumatic Drugs by Serostatus Among Patients With Rheumatoid Arthritis

OBJECTIVE

The objective of this study was to compare the clinical effectiveness of biologic disease-modifying antirheumatic drugs (bDMARDs) or Janus kinase inhibitors (JAKi) among seropositive versus seronegative patients with rheumatoid arthritis (RA) in a real-world setting.

METHODS

We used Optum's deidentified Clinformatics Data Mart Database (January 1, 2004, to March 31, 2021) linked with outpatient laboratory test results. The study population was adult patients with RA who initiated a bDMARD or JAKi. The index date was the dispensing of the first-ever study drug. At least 1-year continuous enrollment before and after the index date was required. Disenrollment due to death after the index date was allowed. Serostatus was defined using laboratory test results or the International Classification of Diseases, 10th Revision code M05x or M06.0x any time prior to the index date. Treatment effectiveness was measured based on a claims-based composite endpoint at 1-year post index, including nonoccurrence of any of the following: addition of conventional synthetic DMARDs, addition of or switching to new bDMARDs/JAKi, initiation of glucocorticoids, increased glucocorticoid dose, or death. Log-binomial regression models were constructed to estimate the risk ratio (RR) with 95% confidence interval (CI) comparing seropositive patients with seronegative patients, adjusting for more than 60 baseline covariates.

RESULTS

We identified a total of 7813 seropositive patients and 4202 seronegative patients. The mean (±SD) age was 56.7 (±14.0) years; 77.9% were female. The risk of 1-year treatment effectiveness was 70.2% among seropositive patients and 69.8% among seronegative patients. The adjusted RR (95% CI) was 1.00 (0.98-1.02).

CONCLUSION

In this real-world cohort study, seropositive and seronegative patients with RA had similar 1-year treatment effectiveness after initiating a bDMARD/JAKi.