Use of ICD-10 diagnosis codes to identify seropositive and seronegative rheumatoid arthritis when lab results are not available

Jeffrey R Curtis,David Salchert,Fenglong Xie,Huifeng Yun,Hong Zhou

doi:10.1186/s13075-020-02310-z

Abstract

BackgroundRheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) antibody tests are often measured at the time of rheumatoid arthritis (RA) diagnosis but may not be repeated and therefore not available in electronic health record (EHR) data; lab test results are unavailable in most administrative claims databases. ICD10 coding allows discrimination between rheumatoid factor positive (M05) (“seropositive”) and seronegative (M06) patients, but the validity of these codes has not been examined.MethodsUsing the ACR’s Rheumatology Informatics System for Effectiveness (RISE) EHR-based registry and U.S. MarketScan data where some patients have lab test results, we assembled two cohorts. Seropositive RA was defined having a M05 diagnosis code on the second rheumatologist encounter, M06 similarly identified seronegative RA, and RF and anti-CCP lab test results were the gold standard. We calculated sensitivity (Se) and positive predicted value (PPV) of the M05/M06 diagnosis codes.ResultsWe identified 43,581 eligible RA patients (RISE) and 1185 (MarketScan) with RF or anti-CCP lab test results available. Using M05 as the proxy for seropositive RA, sensitivity = 0.76, PPV = 0.82 in RISE, and Se = 0.73, PPV = 0.84 in MarketScan. Results for M06 as a proxy for seronegative RA were comparable in RISE, albeit somewhat lower in MarketScan. Over 3 consecutive visits, approximately 90% of RA patients were coded consistently using either M05 or M06 at each visit.ConclusionUnder ICD10, M05 and M06 diagnosis codes are reasonable proxies to identify seropositive and seronegative RA with high sensitivity and positive predictive values if lab test results are not available.

Highlights

Rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) antibody tests are often measured at the time of rheumatoid arthritis (RA) diagnosis but may not be repeated and not available in electronic health record (EHR) data; lab test results are unavailable in most administrative claims databases
In rheumatology, the previous diagnosis code most commonly used for rheumatoid arthritis (ICD-9 714.0) that provided no information about lab testing was replaced with a family of codes to describe patients as being positive for the rheumatoid factor (RF) lab test, e.g., M05.0 “rheumatoid arthritis with rheumatoid factor” or negative for RF (e.g., M06.0) “rheumatoid arthritis without rheumatoid factor”
Given that RF is an important biomarker of prognostic significance for clinical and radiographic outcomes for RA patients [5,6,7], the availability of these International Classification of Diseases (ICD)-10 codes is potentially valuable for clinical research when using data sources where the actual lab results are not available

Summary

Introduction

Rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) antibody tests are often measured at the time of rheumatoid arthritis (RA) diagnosis but may not be repeated and not available in electronic health record (EHR) data; lab test results are unavailable in most administrative claims databases. In rheumatology, the previous diagnosis code most commonly used for rheumatoid arthritis (ICD-9 714.0) that provided no information about lab testing was replaced with a family of codes to describe patients as being positive for the rheumatoid factor (RF) lab test, e.g., M05.0 “rheumatoid arthritis with (positive) rheumatoid factor” or negative for RF (e.g., M06.0) “rheumatoid arthritis without rheumatoid factor”. Given that RF is an important biomarker of prognostic significance for clinical and radiographic outcomes for RA patients [5,6,7], the availability of these ICD-10 codes is potentially valuable for clinical research when using data sources where the actual lab results are not available

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Discussion

Conclusion