# Effect of race and sex on lupus diagnosis in primary care: A randomized factorial survey study

## TL;DR

This study found that a patient's race and sex affect how likely doctors are to correctly diagnose lupus, with Black females more likely to be correctly diagnosed than White males.

## Contribution

The study reveals diagnostic bias in primary care physicians based on patient race and sex using a randomized factorial survey.

## Key findings

- 63.9% of PCPs correctly identified SLE at initial presentation, with the highest accuracy for Black female cases (72.2%) and lowest for White male cases (55.3%).
- Review time was longest for White male cases with correct initial diagnoses, suggesting potential uncertainty or bias.
- Diagnostic accuracy did not improve after reviewing lab results, indicating persistent bias in decision-making.

## Abstract

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune rheumatic disease whose epidemiology and clinical prognosis vary by race and sex. Observed disparities in SLE may be partly attributable to cognitive processes in clinical decision-making, which can influence diagnostic accuracy and clinical management. We aimed to examine variation in primary care physicians’ (PCP) diagnosis and management of SLE when all content of a clinical case is identical, apart from race and sex.

We distributed an online randomized factorial survey from 04/11/2024–06/10/2024 to PCPs across the US. Participants were presented with one of four possible SLE vignettes – Black female, White female, Black male, White male – for which all other clinical content was identical. Block randomization was used to randomly modify the race (Black/White) and sex (female/male) of the SLE “case”. Primary outcomes were correct text-based responses for SLE diagnosis at initial case presentation and after reviewing additional lab results. Secondary outcomes were participants’ review time and planned next steps (treatment, referral, tests) as a proxy for cognitive bias and certainty, respectively. We calculated descriptive statistics for all outcomes stratified by assigned randomized factor and used chi-square tests to evaluate between-group differences.

1031 PCPs (42.7% women, mean age 52.1 ± 12.1 years) completed the case. At initial presentation, 63.9% of participants correctly identified SLE as a differential diagnosis. An initial diagnosis of SLE significantly differed by the race and sex of the case (p < 0.001), with the highest proportion of correct diagnoses occurring for Black female cases (72.2%) and lowest for White male cases (55.3%). Median review time for correct initial diagnoses was longest for White male cases (175 s). After participants reviewed lab results, the overall proportion assigning a final diagnosis of SLE (63.9%) remained unchanged from the initial diagnosis.

A patient’s race and sex may influence diagnostic accuracy and clinical decision-making for SLE in primary care. The observed variation in diagnostic accuracy, which aligns with the descriptive epidemiology of SLE, highlights the need for targeted interventions to ensure equitable diagnostic processes.