# A study of clinical manifestations and associated factors in photosensitive patients with systemic lupus erythematosus

## TL;DR

This study finds that photosensitivity in lupus patients is linked to specific symptoms and immune markers, which could help diagnose lupus earlier.

## Contribution

The study identifies distinct clinical and immunological factors associated with photosensitivity in SLE patients.

## Key findings

- Photosensitivity is more common in female and younger SLE patients.
- Rash, alopecia, and arthritis are clinical features associated with photosensitivity in SLE.
- Anti-Sm/SSA/SSB antibodies and decreased C3/C4 levels are immunological markers linked to photosensitivity.

## Abstract

Photosensitivity (PSN) is a common initial symptom of systemic lupus erythematosus (SLE). This study compared the clinical characteristics of PSN-SLE and non-PSN-SLE patients, analyzed their phenotypic differences and PSN-associated factors, and explored the diagnostic value of PSN for early SLE identification.

A retrospective analysis was conducted on clinical data of SLE patients hospitalized at Taian 88 Hospital of China Rongtong Medical Healthcare Group Co. Ltd between October 2016 and October 2024. Patients were divided into photosensitive and non-photosensitive groups based on physician-confirmed PSN (defined as pathological skin reactions to ultraviolet radiation documented by at least two independent clinicians). Epidemiological, clinical, and immunological differences were compared, and PSN-associated factors were analyzed using SPSS 24.0. Normality tests (Shapiro–Wilk test) were performed for continuous variables; parametric tests (t-test) were used for normally distributed data, and non-parametric tests (Mann–Whitney U-test) for non-normally distributed data.

The overall PSN incidence in SLE patients was 36.59% (101/276). PSN was significantly more prevalent in female patients (95.05% vs. 86.86%, P < 0.05) and patients aged < 40 years and 40–60 years (79.21% vs. 60.57%, P < 0.05). Median (interquartile range) age at diagnosis was 41.0 (29.0–54.0) years for the total cohort, 39.0 (28.0–52.0) years for the PSN group, and 44.0 (31.0–56.0) years for the non-PSN group. PSN-SLE patients had a higher initial diagnosis accuracy (55.45% vs. 35.43%, P < 0.05). Multivariate logistic regression identified rash (OR = 21.019, 95%CI 5.473–80.728), alopecia (OR = 5.940, 95%CI 1.658–21.281), arthritis (OR = 1.889, 95%CI 1.045–3.416), Raynaud syndrome (OR = 2.641, 95%CI 1.443–4.834), anti-Sm antibody (OR = 1.408, 95%CI 1.091–1.818), anti-SSA antibody (OR = 2.337, 95%CI 1.510–3.615), anti-SSB antibody (OR = 3.084, 95%CI 1.519–6.626), decreased C3 (OR = 14.308, 95%CI 3.526–58.061), decreased C4 (OR = 3.429, 95%CI 1.321–8.904), and RF positivity (OR = 10.640, 95%CI 2.173–52.093) as independent PSN-associated factors.

PSN is more common in female and young-to-middle-aged SLE patients. It correlates with distinct clinical (rash, alopecia, arthritis, Raynaud syndrome) and immunological (anti-Sm/SSA/SSB antibodies, decreased C3/C4, RF positivity) features. Routine screening of these markers in PSN patients may facilitate early SLE diagnosis.

The online version contains supplementary material available at 10.1186/s40001-025-03795-7.