A Study of Clinical Features and Associated Factors in Photosensitive Patients with Systemic Lupus Erythematosus

OBJECTIVE: Some patients with systemic lupus erythematosus (SLE) exhibit atypical clinical manifestations, leading to misdiagnosis or missed diagnosis. Photosensitivity is one of the common initial symptoms in SLE, which is often overlooked in early stage due to the absence of other symptoms. This study provides evidence for a regular screening and follow-up system for photosensitive patients by comparing the clinical features of photosensitive and non-photosensitive patients and by analyzing their different clinical manifestations and factors associated with photosensitivity. It is expected that the system will facilitate early identification and warning of SLE-predisposed patients through regular follow-up and screening targeting photosensitive patients, thereby achieving early treatment and improving prognosis. METHODS: A retrospective analysis was conducted on clinical data of SLE patients hospitalized at our hospital between October 2016 and October 2024. All diagnoses were made according to the SLE classification and evaluation criteria recommended by the American College of Rheumatology (ACR) in 1997. General characteristics, clinical data and immunological indicators were collected. The patients were divided into photosensitive and non-photosensitive groups for comparing the differences in epidemiological and clinical features and analyzing the factors associated with photosensitivity. Analysis was performed with statistical software SPSS 24.0. RESULTS: An epidemiological analysis was performed on sex, age and accuracy rate of initial diagnosis. A total of 276 SLE patients were included, comprising 28 males (10.14%) and 248 females (89.86%). The patients were divided into a photosensitive group (n=101, 36.59%) and a non-photosensitive group (n=175, 63.41%). The photosensitive group consisted of 96 female patients (95.05%) and 5 male patients (4.95%), and the non-photosensitive group consisted of 152 female patients (86.86%) and 23 male patients (13.14%). A significantly higher prevalence of photosensitivity was found in female SLE patients than in males (P<0.05). In the photosensitive group, 80 patients (79.21%) were <50 years old and 21 (20.79%) were ≥50 years old. In contrast, the non-photosensitive group included 106 patients <50 years old (60.57%) and 69 patients ≥50 years old (39.43%). Accordingly, SLE patients <50 years old had a significantly higher incidence of photosensitivity than those ≥50 years old (P<0.05). Regarding accuracy rate of initial diagnosis, 56 patients (55.45%) in the photosensitive group were correctly diagnosed with SLE at initial diagnosis, while 45 (44.56%) were undiagnosed or misdiagnosed. In the non-photosensitive group, 62 patients (35.43%) were correctly diagnosed with SLE at initial diagnosis, while 130 (64.57%) were undiagnosed or misdiagnosed. The non-photosensitive group had significantly lower diagnostic accuracy or higher misdiagnosis rates (P<0.05). In terms of clinical manifestations, the photosensitive group showed significantly higher percentages compared to the non-photosensitive group in rash (100, 99.01% vs. 89, 50.86%), alopecia (62, 61.39% vs. 65, 37.14%), arthritis (72, 71.29% vs. 100, 57.14%), and Raynaud syndrome (21, 20.79% vs. 17, 9.71%) (all P<0.05). Conversely, the non-photosensitive group had significantly higher percentages compared to the photosensitive group in terms of sjogren (76, 43.43% vs. 31, 30.69%), fever (82, 46.86% vs. 31, 30.69%), and hematological damage (104, 59.43% vs. 44, 43.56%) (all P<0.05). No significant difference was observed in SLEDAI scores between the photosensitive group and the non-photosensitive group (18.54 ± 9.85 vs. 21.87 ± 8.82) (P>0.05). As for immunological indicators, the photosensitive group exhibited significantly higher percentages than the non-photosensitive group in terms of positive results for anti-SSA antibody (73, 72.28% vs. 99, 56.57%), anti-Sm antibody (41, 40.59% vs. 49, 28.00%), and anti-SSB antibody (31, 30.69% vs. 26, 11.43%) (all P<0.05). The number of patients with decreased C3, decreased C4, and RF positive in the photosensitive group was 82 (81.19%), 59 (58.42%), and 31 (30.69%) respectively, representing significantly higher percentages than those in the non-photosensitive group (121, 69.14%; 76, 43.43%; 24, 13.71%) (all P<0.05). ANA positive rate approached 100% in both groups. Multivariate logistic regression analysis revealed that rash, alopecia, arthritis, Raynaud syndrome, anti-Sm antibody, anti-SSA antibody, anti-SSB antibody, decreased C3, decreased C4 and RF positive were the main factors associated with photosensitivity. CONCLUSION: 1. Photosensitivity was significantly more prevalent in female SLE patients and those aged <50 years old compared to male patients and other age groups. Photosensitive SLE patients had significantly higher rates of rash, alopecia, arthritis and Raynaud syndrome. Additionally, these patients showed significantly higher positive rates of anti-Sm antibody, anti-SSA antibody, anti-SSB antibody, RF, as well as lower C3 and C4 compared to non-photosensitive SLE patients. 2. Multivariate analysis revealed significant positive correlations between photosensitivity and physical symptoms (e.g., rash, alopecia, arthritis, and Raynaud syndrome) as well as abnormal indicators (e.g., anti-Sm antibody, anti-SSA antibody, anti-SSB antibody, RF positive, decreased C3, and decreased C4. 3. For photosensitive patients with no other sings of SLE, routine screening of these physical signs and laboratory indicators may facilitate the identification of individuals with SLE predisposition or in their early onset.