Introduction
As an autoimmune photosensitive skin condition, cutaneous lupus erythematosus (CLE) can lead to several cosmetic and vocational disabilities, severely limiting quality of life. Recent studies demonstrated CLE’s profound impact on quality of life1–4, but few have examined the association between income and quality of life in CLE patients.
It is well-known that income has a profound effect on overall health, life expectancy, and quality of life in different diseases.5–8 In psoriasis, quality of life has been shown to be affected by financial status, with a significantly negative correlation between family income and quality of life based on a skin-specific quality of life questionnaire, the Dermatology Life Quality Index (DLQI).9 However, the impact of income on quality of life has been incompletely characterized in cutaneous lupus. We previously reported that lower socioeconomic status was predictive of overall poor quality of life in 73 CLE patients.1 These findings were limited by a small sample size and univariate analyses. Thus, larger studies are needed to further investigate the relationship of socioeconomic status and quality of life in patients with CLE. A better understanding of this relationship can help clinicians understand the challenges that individuals with CLE face as a result of their income status.
To address this knowledge gap, we used the University of Texas Southwestern (UTSW) CLE Registry, which includes CLE patients of different socioeconomic status, to design a three-part study. First, we sought to compare quality of life, as measured by the SKINDEX-29+3 subdomain scores, amongst CLE patients of different annual income levels. Next, we identified which specific aspects of quality of life, as measured by individual SKINDEX-29+3 questions, are most frequently impaired in CLE patients of various incomes. Finally, we aimed to determine significant factors of CLE patients earning less than 10,000 United States Dollars (USD) per year associated with worse quality of life.
Patients and Methods
Patient Population
This was a cross-sectional pilot study of CLE patients enrolled in the UTSW CLE Registry who were seen at their initial study visit from April 2009 to September 2018 in outpatient dermatology clinics at UTSW Medical Center and Parkland Health and Hospital System. All patients had their CLE diagnosis confirmed by a dermatologist (BFC) via clinicopathological correlation. Participants who self-reported annual income information and completed the SKINDEX-29+3 at their study visit were included in the study. The study was approved by the Institutional Review Board of UTSW, and all participants provided written informed consent. Variables
The primary outcome variable was the SKINDEX-29+3 score. The SKINDEX-29 is a 29-question, validated skin-specific quality of life questionnaire that can be broken down into three subdomains: symptoms, emotions, and functioning.10–12 Three additional questions directed towards CLE patients were also added as a lupus-specific domain, thus designating the questionnaire SKINDEX-29+3.1, 2 Scores are calculated on a 5-point Likert scale – “Never, Rarely, Sometimes, Often, All the Time” – with values assigned at 25-point increments (i.e. 0, 25, 50, 75, 100). Higher scores indicate poorer quality of life.
The primary predictor variable was individual annual income. Patients provided annual income information by selecting one of the three categories: less than 10,000 USD, between 10,000 USD and 50,000 USD, and greater than 50,000 USD. Cutoffs of 10,000 USD and 50,000 USD were designated to approximate the poverty and median level incomes in the United States.13, 14 Additional predictor variables included age, sex, race/ethnicity, disease duration, CLE subtype, education level, smoking status, systemic lupus erythematosus (SLE) diagnosis, and skin disease severity scores, specifically Cutaneous Lupus Activity and Severity Index (CLASI) activity and damage scores. The CLASI activity score assesses erythema, scale/hyperkeratosis, mucous membrane involvement, and non-scarring hair loss, while the CLASI damage score assesses dyspigmentation and scarring, including scarring hair loss.15
Statistical Analysis
Sample size was not calculated since this was a pilot study. Demographic and clinical variables were reported as medians and interquartile ranges (IQR) or frequencies. Univariate and multivariable analyses were performed to identify predictor variables associated with poor quality of life. Kruskal-Wallis test with Tukey-type multiple comparisons using the Dunn method was performed to compare SKINDEX-29+3 subdomain scores across the three income categories. Among those making <10,000 USD per year, Kruskal-Wallis or Mann-Whitney U tests were performed to determine which predictor variables were associated with worse SKINDEX-29+3 subdomain scores. The aforementioned predictor variables were analyzed in a multivariable linear regression model to determine which combination of variables were predictors for SKINDEX-29+3 emotions, symptoms, function and lupus-specific subdomains. This was done for all patients, and then separately for those making <10,000 USD. We selected important predictors to include in each of the models, performed a stepwise regression, and then fit a final regression model using the information from the stepwise regression results to guide our selection of the best predictors. Significance was set at p<0.05. Chi-square tests were used to assess how responses to each individual SKINDEX-29+3 question varied across income groups. The 5-point Likert scale of responses was condensed to a 3-point scale for this analysis. “Never” and “rarely,” and “often” and “all the time” were combined into two separate categories, and “sometimes” remained its own category. Significance was set at p<0.001 to account for multiple comparisons. All statistical analyses were performed using SPSS, version 25 (Armonk, NY).
Results
A total of 341 out of 368 patients (92.7%) completed the surveys. 61 patients with incomplete SKINDEX-29+3 questionnaires and 42 patients with missing income were excluded. Therefore, 238 patients were included in this study. Table 1 displayed the demographic and clinical characteristics of all participants stratified by income. The majority of patients earned between 10,000 USD-50,000 USD (n=88) or <10,000 USD (n=85) per year. Age increased as annual income increased (p<0.001). Females (p=0.318) and chronic CLE patients (p=0.038) were the most predominant sex and subtype across all income brackets. Caucasians had the largest proportion in the highest income bracket (58.5%), while African Americans had the largest proportion in the lowest income bracket (67.1%) (p<0.001). CLASI activity scores did not differ significantly across income, while CLASI damage scores displayed an inverse relationship with income level (p=0.006).
Table 1:
Demographic and clinical characteristics of cutaneous lupus patients by annual income
| Characteristic | All patients (n=238) | <10K USD (n=85) | 10–50K USD (n=88) | >50K USD (n=65) | P Valuea |
|---|---|---|---|---|---|
| Age (y), median (IQR) | <0.001 | ||||
| 37 (27–46) | 31 (21–44) | 36 (29–44) | 43 (33.25–49.5) | ||
| Sex, n (%) | 0.318 | ||||
| Female | 196 (82%) | 70 (82%) | 76 (86%) | 50 (77%) | |
| Male | 42 (18%) | 15 (18%) | 12 (14%) | 15 (23%) | |
| Race/Ethnicity, n (%) | <0.001 | ||||
| African American | 123 (52%) | 57 (67.1%) | 44 (50%) | 22 (33.8%) | |
| Hispanic | 19 (8%) | 9 (11%) | 10 (11%) | 0 (0%) | |
| Caucasian | 82 (35%) | 14 (16.5%) | 30 (34%) | 38 (58.5%) | |
| Asian | 9 (3.8%) | 4 (4.7%) | 2 (2.3%) | 3 (4.6%) | |
| Mixed | 5 (5%) | 2 (1.2%) | 2 (2.3%) | 2 (3.1%) | |
| Education n (%)b | <0.001 | ||||
| Less than High School | 20 (9%) | 15 (19%) | 5 (6%) | 0 (0%) | |
| High School | 74 (33%) | 38 (49%) | 24 (29%) | 12 (19%) | |
| College | 102 (46%) | 22 (28%) | 47 (57%) | 33 (52%) | |
| Graduate Degree | 27 (12%) | 3 (4%) | 6 (7%) | 18 (29%) | |
| CLE Subtypes, n (%) | 0.038 | ||||
| Acute CLE | 16 (7%) | 7 (8%) | 8 (9%) | 1 (1.5%) | |
| Subacute CLE | 36 (15%) | 7 (8%) | 19 (22%) | 15 (15%) | |
| Chronic CLE | 186 (78%) | 71 (84%) | 61 (69%) | 54 (83%) | |
| CLASI component score, median (IQR) | |||||
| Activity | 4 (2–8) | 4 (2–10) | 3 (1–8.25) | 3 (0.25–6) | 0.218 |
| Damage | 5 (1–11) | 8 (2–15) | 5 (1–9.25) | 4 (1–9.25) | 0.006 |
| Disease duration (y), median (IQR) | 0.634 | ||||
| 4.4 (0.9–12) | 5 (1–12.6) | 3.5 (0.9–11) | 3.5 (0.8–11) | ||
| SLE diagnosis, n (%) | 0.095 | ||||
| Yes | 121 (51%) | 49 (58%) | 46 (52%) | 26 (40%) | |
| No | 117 (49%) | 36 (42%) | 42 (48%) | 39 (60%) | |
| Current smoker, n (%)c | 0.625 | ||||
| Yes | 78 (37%) | 33 (41%) | 26 (33.3%) | 19 (38%) | |
| No | 133 (63%) | 48 (59%) | 52 (66.6%) | 33 (64%) |
Abbreviations: CLASI, Cutaneous Lupus Erythematosus Area Severity Index; CLE, Cutaneous Lupus Erythematosus; IQR, Interquartile range; SLE, Systemic Lupus Erythematosus.
P-values for continuous variables were computed with Mann-Whitney U or Kruskal Wallis test. P-values for categorical variables were computed with chi-square test.
Education level is missing for 15 patients.
Smoking history is missing for 27 patients.
Comparison of SKINDEX-29+3 subdomain scores across annual income groups
SKINDEX-29+3 subdomain scores were compared among CLE patients in different annual income categories (Figure 1). All four SKINDEX-29+3 subdomain scores decreased as annual income increased. There was a significant difference between the <10,000 USD and >50,000 USD category in all subdomains (p<0.05 for lupus-specific, p<0.01 for function and symptom, p<0.001 for emotions). To control for other factors that could affect quality of life (e.g. gender, disease activity), we performed a multivariable analysis to determine which income categories were predictive of SKINDEX-29+3 subdomain scores. The relationship between lower income and poorer quality of life persisted in the emotions (p=0.001) and symptom (p<0.001) subdomains after controlling for other demographic measures (Table 2).
Figure 1: Differences in SKINDEX-29+3 subdomains in CLE patients with annual income of <10K USD, 10–50K USD, and >50K USD.
A: Function subdomain (p < 0.001) B: Emotions subdomain (p < 0.001), and C: Symptoms subdomain (p = 0.001) demonstrated significantly higher scores (or worse quality of life) for the <10,000 USD/yr group compared with the other two groups. D: Lupus subdomain (p = 0.018) revealed significance between the bottom and top income groups only. Independent sample Kruskal-Wallis tests were performed. *: P < 0.05, **: P < 0.01, ***: P < 0.001.
Table 2:
R Multiple linear regression analyses of SKINDEX-29+3 subdomain scores in all patients with CLE (N=238)
| Subscale | Emotions Subscale | Symptoms Subscale | Function Subscale | Lupus Subscale | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| B | Std Error | p value | 95% CI | B | Std Error | p value | 95% CI | B | Std Error | p value | 95% CI | B | Std Error | p value | 95% CI | |
| Constant | 47.4 | 7.8 | <0.001 | (32.1, 62.8) | 28.9 | 3.85 | <0.001 | (21.3, 36.4) | 28.4 | 7.29 | <0.001 | (14.1, 42.8) | 49.5 | 7.63 | <0.001 | (34.4, 64.5) |
| Income | −7.4 | 2.3 | 0.001 | (−11.90, −2.88) | −5.95 | 1.69 | <0.001 | −9.27, −2.63) | - | - | - | - | - | - | - | - |
| Acute CLE | −21.4 | 7.3 | 0.004 | (−35.93, −6.97) | −8.03 | 5.37 | 0.136 | (−18.6, 2.55) | −16.1 | 6.95 | 0.021 | (−29.8, −2.42) | −19.3 | 7.45 | 0.010 | (−34.0, −4.61) |
| Sex | 17.3 | 4.7 | <0.001 | (8.08, 26.5) | 14.48 | 3.46 | <0.001 | (7.67, 21.3) | 15.7 | 4.41 | <0.001 | (6.96, 24.4) | 28.8 | 4.69 | <0.001 | (19.5, 38.0) |
| Smoking Status | 13.1 | 3.7 | 0.001 | (5.74, 20.5) | - | - | - | - | 11.0 | 3.53 | 0.002 | (3.99, 17.9) | - | - | - | - |
| CLASI Activity | 0.58 | 0.3 | 0.040 | (0.03, 1.15) | 1.04 | 0.21 | <0.001 | (0.63, 1.46) | 0.80 | 0.27 | 0.003 | (0.27, 1.33) | 0.79 | 0.29 | 0.006 | (0.22, 1.36) |
| Age | −0.31 | 0.13 | 0.021 | (−0.57, −0.05) | - | - | - | - | −0.36 | 0.12 | 0.004 | (−0.61, −0.12) | −0.37 | 0.14 | 0.007 | (−0.64, −0.10) |
| Asian | - | - | - | - | −18.3 | 6.91 | 0.009 | (−31.9, −4.69) | - | - | - | - | - | - | - | - |
| R | F | p value | R | F | p value | R | F | p value | R | F | p value | |||||
| Regression statistics | 0.485 | 10.4 | <0.001 | 0.494 | 14.9 | <0.001 | 0.437 | 9.67 | <0.001 | 0.452 | 15.0 | <0.001 | ||||
Abbreviations: CI, Confidence Interval; CLASI, Cutaneous Lupus Erythematosus Area Severity Index; CLE, Cutaneous Lupus Erythematosus; Std Error, Standard Error
Differences in specific QoL aspects across income groups
Answers to individual SKINDEX-29+3 questions between income groups were compared, with those revealing a statistically significant difference between income groups in Figure 2. In all nine of thirty-two of these questions, patients with annual incomes <10,000 USD answered “often” or “all the time” more frequently than those from the other income groups. Five questions came from the function subdomain – “Skin affects social life”, “Stay at home due to my skin”, “Do things by myself due to my skin”, “Skin affects interactions with others” and “Skin affects desire to be with people” (p≤0.001). Four questions were part of the emotion subdomain – “I worry about getting scars”, “I am ashamed of my skin”, “My skin makes me angry” and “I am embarrassed by my skin” (p≤0.001). Cronbach’s alpha for both 5 item and the 3 item scales were 0.965 and 0.957, respectively, indicating that the 3-item classification was a good representation.
Figure 2. SKINDEX-29+3 questions with significantly different scores in CLE patients with annual income of <10K USD, 10–50K USD and >50K USD.
Percentages of those with incomes less than 10,000 USD per year answering “Often” or “All the time” were higher on 5 function questions (dark grey background) and 4 emotion questions (light grey background) than those with annual incomes ranging from 10,000–50,000 USD per year or greater than 50,000 USD per year (p ≤ 0.001). ***: p=0.001, ****: p<0.001.
Identification of factors associated with worse quality of life in CLE patients with annual incomes <10,000 USD
Among those making <10,000 USD per year, we sought to identify characteristics predisposing CLE patients to experiencing worse quality of life impairment. In univariate analyses, CLE patients with significant impairment in the emotion subdomain were more likely to be less than 40 years of age (p=0.010), female (p=0.014), smokers (p = 0.017) and have chronic CLE (p=0.039) (Table 3). Regarding the symptoms subdomain, females (p=0.001), those with CLASI activity scores ≥10 (p=0.016) and smokers (p=0.012) had significantly worse scores. Patients who were younger than 40 years of age (p=0.042), females (p=0.015), had chronic CLE (p=0.044), CLASI activity (p=0.001) and damage scores ≥10 (p=0.033) and smoked (p=0.004) experienced the most impairment in the function subdomain. Regarding the lupus subdomain, only females (p=0.001) had significantly worse scores. In multivariable analysis, females, smokers and younger patients were associated with greater emotional impairment while acute CLE was associated with less emotional impairment. Female sex, increased CLASI activity scores and smoking were significantly associated with the symptoms subscale. Functional impairment was worse among females and smokers. Female sex and increased CLASI activity scores were also associated with worse quality of life in the lupus subdomain (Table 4).
Table 3:
Univariate analyses of SKINDEX-29+3 subdomain scores among CLE subgroups within patients making <10,000 USD per year.
| Characteristic | N=85 N (%) | Emotions Subdomain | Symptoms Subdomain | Function Subdomain | Lupus Subdomain |
|---|---|---|---|---|---|
| Median (IQR) | Median (IQR) | Median (IQR) | Median (IQR) | ||
| Age | |||||
| <40 | 38 (45%) | 60 (40–75) | 46 (29–71) | 40 (23–60) | 83 (58–92) |
| ≥40 | 47 (55%) | 48 (20–78) | 46 (29–61) | 33 (17–65) | 75 (33–92) |
| P Valuea | 0.010 | 0.281 | 0.042 | 0.073 | |
| Sex | |||||
| Female | 70 (82%) | 60 (40–80) | 48 (36–67) | 39 (23–65) | 75 (58–92) |
| Male | 15 (18%) | 35 (15–55) | 29 (11–39) | 19 (8–40) | 25 (8–75) |
| P Valuea | 0.014 | 0.001 | 0.015 | 0.001 | |
| Race | |||||
| African American | 57 (67%) | 58 (35–78) | 46 (29–67) | 40 (17–63) | 75 (50–92) |
| Caucasian | 14 (16%) | 66 (28–80) | 50 (36–64) | 39 (27–75) | 67 (50–83) |
| Others | 14 (16%) | 48 (43–68) | 41 (25–46) | 29 (19–38) | 83 (75–92) |
| P Valuea | 0.842 | 0.338 | 0.424 | 0.561 | |
| Educationb | |||||
| Less than High School | 15 (19%) | 55 (14–79) | 50 (38–62) | 38 (24–61) | 58 (38–75) |
| High School | 38 (49%) | 46 (33–78) | 44 (29–61) | 34 (15–60) | 75 (33–92) |
| College | 22 (28%) | 69 (45–73) | 52 (32–61) | 39 (23–65) | 83 (67–100) |
| Graduate Degree | 3 (4%) | 75 (64–78) | 36 (36–48) | 40 (35–41) | 58 (54–75) |
| P Valuea | 0.364 | 0.768 | 0.818 | 0.234 | |
| CLE Subtypes | |||||
| Acute CLE | 7 (8%) | 35 (3–48) | 36 (11–71) | 4 (0–23) | 50 (17–92) |
| Subacute CLE | 7 (8%) | 43 (28–75) | 36 (25–54) | 29 (17–60) | 58 (33–100) |
| Chronic CLE | 71 (84%) | 60 (38–80) | 46 (29–64) | 38 (23–63) | 75 (50–92) |
| P Valuea | 0.039 | 0.410 | 0.044 | 0.617 | |
| CLASI Activity | |||||
| <10 | 64 (75%) | 48 (25–75) | 43 (29–61) | 31 (15–60) | 75 (33–92) |
| ≥10 | 21 (25%) | 66 (45–85) | 52 (46–68) | 60 (40–67) | 83 (67–100) |
| P Valuea | 0.053 | 0.016 | 0.001 | 0.052 | |
| CLASI Damage | |||||
| <10 | 50 (59%) | 48 (25–73) | 46 (29–61) | 31 (15–58) | 75 (33–92) |
| ≥10 | 35 (41%) | 65 (44–85) | 52 (34–65) | 47 (29–66) | 75 (63–92) |
| P Valuea | 0.090 | 0.460 | 0.033 | 0.583 | |
| SLE Diagnosis | |||||
| Yes | 49 (58%) | 69 (30–83) | 46 (29–61) | 39 (19–69) | 75 (33–96) |
| No | 36 (42%) | 48 (38–73) | 46 (32–67) | 38 (17–60) | 75 (50–92) |
| P Valuea | 0.385 | 0.428 | 0.493 | 0.683 | |
| Current Smokerc | |||||
| Yes | 48 (59%) | 70 (45–85) | 61 (43–71) | 60 (35–69) | 75 (58–92) |
| No | 33 (41%) | 45 (24–71) | 39 (27–54) | 31 (15–47) | 75 (33–92) |
| P Valuea | 0.017 | 0.012 | 0.004 | 0.383 |
Abbreviations: CLASI, Cutaneous Lupus Erythematosus Area Severity Index; CLE, Cutaneous Lupus Erythematosus; IQR, Interquartile range; SLE, Systemic Lupus Erythematosus
Values computed with Mann-Whitney U test or Kruskal Wallis test
Education level missing for 7 patients.
Smoking history is missing for 4 patients
Table 4:
Multiple linear regression analyses of SKINDEX-29+3 subdomain scores in patients with CLE making <10,000 USD (N=85)
| Subscale | Emotions Subscale | Symptoms Subscale | Function Subscale | Lupus Subscale | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| B | Std Error | p value | 95% CI | B | Std Error | p value | 95% CI | B | Std Error | p value | 95% CI | B | Std Error | p value | 95% CI | |
| Constant | 49.0 | 10.2 | <0.001 | (28.7, 69.3) | 16.8 | 5.56 | 0.003 | (5.73, 27.9) | 9.51 | 6.45 | 0.145 | (−3.34, 22.4) | 32.1 | 7.44 | <0.001 | (17.3, 46.9) |
| Acute CLE | −29.9 | 10.7 | 0.006 | −51.1, −8.67) | - | - | - | - | - | - | - | - | - | - | - | - |
| Sex | 28.7 | 7.18 | <0.001 | (14.4, 43.0) | 22.8 | 5.52 | <0.001 | (11.8, 33.8) | 18.5 | 6.41 | 0.005 | (5.72, 31.3) | 32.0 | 7.82 | <0.001 | (16.4, 47.6) |
| Smoking Status | 18.7 | 5.76 | 0.002 | (7.24, 30.2) | 11.6 | 4.43 | 0.010 | (2.81, 20.4) | 15.0 | 5.14 | 0.005 | (4.74, 25.2) | - | - | - | - |
| Age | −0.55 | 0.20 | 0.006 | (−0.94, −0.16) | - | - | - | - | - | - | - | - | - | - | - | - |
| CLASI Activity | - | - | - | - | 0.87 | 0.35 | 0.015 | (0.17, 1.56) | - | - | - | - | 1.24 | 0.47 | 0.010 | (0.30, 2.17) |
| R | F | p value | R | F | p value | R | F | p value | R | F | p value | |||||
| Regression | 0.55 | 8.47 | <0.00 | 0.55 | 11.3 | <0.00 | 0.57 | 12.9 | <0.00 | 0.49 | 13.2 | <0.00 | ||||
| 5 | 1 | 3 | 1 | 8 | 1 | 4 | 1 | |||||||||
Abbreviations: CI, Confidence Interval; CLASI, Cutaneous Lupus Erythematosus Area Severity Index; CLE, Cutaneous Lupus Erythematosus; Std Error, Standard Error
Discussion
Our study investigated quality of life differences in CLE patients from different socioeconomic status and further delineated which specific quality of life aspects were most frequently impaired. Our results confirmed prior observations that lower annual income was associated with poorer overall quality of life.1 In univariate analysis, we found that individuals making <10,000 USD per year had the greatest impairment in quality of life throughout all four subdomains of the SKINDEX-29+3. After controlling for other risk factors via multivariable analysis, income was independently associated with emotions and symptom subdomains. Additionally, we uniquely identified that low-income CLE individuals experience more shame, anger, embarrassment and social isolation related to their skin disease. We also determined which patient subgroups among those making less than 10,000 USD per year experience worse impairment in specific SKINDEX-29+3 subdomains. These included females, patients younger than 40 years of age, smokers, and those with more active skin disease. This study is important for understanding how to best support low income CLE patients, and make appropriate referrals to address their needs.
In the United States, the poverty line is currently 12,760 USD for a one-person household and 26,200 USD for a family of four,13 while the median salary was around 63,179 USD.14 Many patients in our cohort reported being around the US poverty line, and came from the Parkland Health and Hospital System, a safety net hospital that provides medical care for a significant proportion of the underserved population in Dallas, Texas. In 2018, Parkland Health and Hospital system had a payor mix of 31.8% Medicaid, 27.5% charity coverage, 16.6% Medicare, or 11.9% self-pay.16 This patient population faces distinct challenges related to their income status, which adds a unique perspective to this study.
Univariate analyses showed that, across all SKINDEX-29+3 domains, patients making <10,000 USD per year experienced significantly worse quality of life, particularly versus those earning >50,000 USD/year. Interestingly, there was also a significant difference between the middle (10–50,000 USD) and highest income groups on three of the four subdomains (function, emotions, symptoms), indicating quality of life impairment is not limited to those in the lowest income bracket. Moreover, there is a gradient between quality of life related to skin disease and income, with one improving as the other increases. Even when controlling for other factors such as race, education level, age, and disease severity, income remained a significant predictor of quality of life in the multivariable analysis. CLE places a substantial financial burden on patients. The estimated average annual incremental cost for CLE was 10,119 USD in 2018.17 The difficulties of being low income compounded with the financial, emotional and physical toll of having CLE likely result in poorer quality of life among low income patients with CLE.
Univariate analyses done on individual SKINDEX-29+3 questions between groups show similar trends amongst income levels. However, two additional themes emerged from this analysis. First, as patients with lower socioeconomic status experienced worse quality of life in the function subdomain of the SKINDEX-29+3, questions revealing significanace between income groups focused upon themes of isolation and communication. The second theme emerged from the other four questions, all of which were part of the emotion subdomain. These questions related to anxiety and embarrassment regarding their skin condition. Social isolation is associated with lower income and poorer health outcomes.18–20 Additionally, lower income and socioeconomic status has been associated with greater internalized social inadequacy, shame, inferiority and increased sense of discrimination.21–23 Low income patients may avoid social gatherings due to these internalized feelings of inferiority as well as financial cost associated with social encounters. There is a complicated relationship between healthcare utilization, isolation and lack of strong social networks. Lack of social support and increased loneliness may increase or decrease patient use of health services.24–26 For low income patients with CLE, feelings of inadequacy about, and perception of bias against their income status may exacerbate negative feelings about their skin condition. This may lead to increased seclusion and a complex relationship with the healthcare system. Clinicians can encourage patients with CLE to establish support networks to increase overall quality of life and make appropriate referrals to help patients cope with their difficulties.
Over one-third of our patients reported earning <10,000 USD/year. Across all states, this group lies below the poverty line for a one-person household. Predictors of low quality of life within this group were mostly similar to that reported of CLE populations2–4, 27. Among this group, we found females experience worse quality of life across all domains, and younger patients more frequently experience emotional impairment. This may be due to decreased self-body image in patients who are younger and female.28 Disease activity is associated with a higher frequency of symptomatic and lupus-specific limitations. This is likely due to increased disease activity causing greater physical discomfort and worry about prolonged sun exposures and hair loss. Additionally, in our cohort we found that acute CLE, in all patients and amongst those making less than 10,000 USD per year, was a predictor of better quality of life in multiple SKINDEX-29 subdomains. Acute CLE typically follows sun-exposure, is transient in nature, and resolves infrequently with dyspigmentation, and without scarring.29 Skin related quality of life is likely better in acute CLE given that the condition is short-lived and resolves with minimal disfigurement. Although patients with acute CLE had better skin related quality of life, this condition is often associated with systemic disease and these patients may have greater impairement in other aspects of health related quality of life.
The limitations of this project include its cross-sectional nature, and single-center design. Nonetheless, the demographics of our CLE cohort is consistent with previous studies,30 and has robust racial and socioeconomic diversity, making it generalizable. Further longitudinal multi-center studies are needed to confirm our findings. Income was also self-reported by patients and could not be verified.
In conclusion, we have shown that income has a proportionate relationship to quality of life in patients with CLE. Specifically, patients with low incomes are more likely to experience limitations relating to social isolation, embarrassment and self-consciousness of their skin more frequently than patients with higher income status. Patients with CLE, especially those with lower income, can be assessed for feelings of anxiety and embarrassment, and evaluated for poor social engagement.
Acknowledgements
The authors would like to thank Rebecca Vasquez, Andrew Kim, Daniel Grabell, Noelle Teske, Tina Vinoya, Jack O’Brien, Elaine Kunzler, Stephanie Florez-Pollack, Jennifer Coias, Danielle Lin, Jenny Raman, and Justin Raman for recruiting patients. The authors would like to thank participants of the University of Texas Southwestern CLE Registry for their contributions to lupus research.
Funding Statement: The research reported in this publication was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health under Award Number K23AR0614415. The content is solely the responsibility of the authors and does not necessarily represent the official views of The University of Texas Southwestern Medical Center at Dallas and its affiliated academic and health care centers, the National Center for Research Resources, and the National Institutes of Health.
Abbreviations:
- CLASI
Cutaneous Lupus Activity and Severity Index
- CLE
Cutaneous lupus erythematosus
- DLQI
Dermatology Life Quality Index
- IQR
Interquartile ranges
- SLE
Systemic lupus erythematosus
- QoL
Quality of life
- USD
United States Dollars
- UTSW
University of Texas Southwestern
Footnotes
Declaration of conflicting interest: Dr. Chong is an investigator for Daavlin Corporation, Biogen Incorporated, and Pfizer Incorporated. He is a consultant for Viela Bio, Beacon Biosciences, GlaxoSmithKline, and Principia Bio. The other authors have no conflicts of interest.
IRB status: Approved by University of Texas Southwestern Medical Center IRB.
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