Olivia Kam, BA

To the Editor:

Psoriasis is a chronic inflammatory condition that affects individuals in various extracutaneous ways.¹ Prior studies have documented a decrease in exercise intensity among patients with psoriasis²; however, few studies have specifically investigated baseline mobility in this population. Baseline mobility denotes an individual’s fundamental ability to walk or move around without assistance of any kind. Impaired mobility—when baseline mobility is compromised—is an aspect of the wider diversity, equity, and inclusion framework that underscores the significance of recognizing challenges and promoting inclusive measures, both at the point of care and in research.³ study sought to analyze the relationship between psoriasis and baseline mobility among US adults (aged 45 to 80 years) utilizing the latest data from the National Health and Nutrition Examination Survey (NHANES) database for psoriasis.⁴ We used three 2-year cycles of NHANES data to create a 2009-2014 dataset.

The overall NHANES response rate among adults aged 45 to 80 years between 2009 and 2014 was 67.9%. Patients were categorized as having impaired mobility if they responded “yes” to the following question: “Because of a health problem, do you have difficulty walking without using any special equipment?” Psoriasis status was assessed by the following question: “Have you ever been told by a doctor or other health professional that you had psoriasis?” Multivariable logistic regression analyses were performed using Stata/SE 18.0 software (StataCorp LLC) to assess the relationship between psoriasis and impaired mobility. Age, income, education, sex, race, tobacco use, diabetes status, body mass index, and arthritis status were controlled for in our models.

Our analysis initially included 9982 participants; 14 did not respond to questions assessing psoriasis and impaired mobility and were excluded. The prevalence of impaired mobility in patients with psoriasis was 17.1% compared with 10.9% among those without psoriasis (Table 1). There was a significant association between psoriasis and impaired mobility among patients aged 45 to 80 years after adjusting for potential confounding variables (adjusted odds ratio [AOR], 1.54; 95% CI, 1.04- 2.29; P=.032)(Table 2). Analyses of subgroups yielded no statistically significant results.

Our study demonstrated a statistically significant difference in mobility between individuals with psoriasis compared with the general population, which remained significant when controlling for arthritis, obesity, and diabetes (P=.032). This may be the result of several influences. First, the location of the psoriasis may impact mobility. Plantar psoriasis—a manifestation on the soles of the feet—can cause discomfort and pain, which can hinder walking and standing.⁵ Second, a study by Lasselin et al⁶ found that systemic inflammation contributes to mobility impairment through alterations in gait and posture, which suggests that the inflammatory processes inherent in psoriasis could intrinsically modify walking speed and stride, potentially exacerbating mobility difficulties independent of other comorbid conditions. These findings suggest that psoriasis may disproportionately affect individuals with impaired mobility, independent of comorbid arthritis, obesity, and diabetes.

These findings have broad implications for diversity, equity, and inclusion. They should prompt us to consider the practical challenges faced by this patient population and the ways that we can address barriers to care. Offering telehealth appointments, making primary care referrals for impaired mobility workups, and advising patients of direct-to-home delivery of prescriptions are good places to start.

Limitations to our study include the lack of specificity in the survey question, self-reporting bias, and the inability to control for the psoriasis location. Further investigations are warranted in large, representative US adult populations to assess the implications of impaired mobility in patients with psoriasis.

To the Editor:

Psoriasis is a chronic inflammatory condition that affects individuals in various extracutaneous ways.¹ Prior studies have documented a decrease in exercise intensity among patients with psoriasis²; however, few studies have specifically investigated baseline mobility in this population. Baseline mobility denotes an individual’s fundamental ability to walk or move around without assistance of any kind. Impaired mobility—when baseline mobility is compromised—is an aspect of the wider diversity, equity, and inclusion framework that underscores the significance of recognizing challenges and promoting inclusive measures, both at the point of care and in research.³ study sought to analyze the relationship between psoriasis and baseline mobility among US adults (aged 45 to 80 years) utilizing the latest data from the National Health and Nutrition Examination Survey (NHANES) database for psoriasis.⁴ We used three 2-year cycles of NHANES data to create a 2009-2014 dataset.

The overall NHANES response rate among adults aged 45 to 80 years between 2009 and 2014 was 67.9%. Patients were categorized as having impaired mobility if they responded “yes” to the following question: “Because of a health problem, do you have difficulty walking without using any special equipment?” Psoriasis status was assessed by the following question: “Have you ever been told by a doctor or other health professional that you had psoriasis?” Multivariable logistic regression analyses were performed using Stata/SE 18.0 software (StataCorp LLC) to assess the relationship between psoriasis and impaired mobility. Age, income, education, sex, race, tobacco use, diabetes status, body mass index, and arthritis status were controlled for in our models.

Our analysis initially included 9982 participants; 14 did not respond to questions assessing psoriasis and impaired mobility and were excluded. The prevalence of impaired mobility in patients with psoriasis was 17.1% compared with 10.9% among those without psoriasis (Table 1). There was a significant association between psoriasis and impaired mobility among patients aged 45 to 80 years after adjusting for potential confounding variables (adjusted odds ratio [AOR], 1.54; 95% CI, 1.04- 2.29; P=.032)(Table 2). Analyses of subgroups yielded no statistically significant results.

Our study demonstrated a statistically significant difference in mobility between individuals with psoriasis compared with the general population, which remained significant when controlling for arthritis, obesity, and diabetes (P=.032). This may be the result of several influences. First, the location of the psoriasis may impact mobility. Plantar psoriasis—a manifestation on the soles of the feet—can cause discomfort and pain, which can hinder walking and standing.⁵ Second, a study by Lasselin et al⁶ found that systemic inflammation contributes to mobility impairment through alterations in gait and posture, which suggests that the inflammatory processes inherent in psoriasis could intrinsically modify walking speed and stride, potentially exacerbating mobility difficulties independent of other comorbid conditions. These findings suggest that psoriasis may disproportionately affect individuals with impaired mobility, independent of comorbid arthritis, obesity, and diabetes.

These findings have broad implications for diversity, equity, and inclusion. They should prompt us to consider the practical challenges faced by this patient population and the ways that we can address barriers to care. Offering telehealth appointments, making primary care referrals for impaired mobility workups, and advising patients of direct-to-home delivery of prescriptions are good places to start.

Limitations to our study include the lack of specificity in the survey question, self-reporting bias, and the inability to control for the psoriasis location. Further investigations are warranted in large, representative US adult populations to assess the implications of impaired mobility in patients with psoriasis.

To the Editor:

Psoriasis is a chronic inflammatory condition that affects individuals in various extracutaneous ways.¹ Prior studies have documented a decrease in exercise intensity among patients with psoriasis²; however, few studies have specifically investigated baseline mobility in this population. Baseline mobility denotes an individual’s fundamental ability to walk or move around without assistance of any kind. Impaired mobility—when baseline mobility is compromised—is an aspect of the wider diversity, equity, and inclusion framework that underscores the significance of recognizing challenges and promoting inclusive measures, both at the point of care and in research.³ study sought to analyze the relationship between psoriasis and baseline mobility among US adults (aged 45 to 80 years) utilizing the latest data from the National Health and Nutrition Examination Survey (NHANES) database for psoriasis.⁴ We used three 2-year cycles of NHANES data to create a 2009-2014 dataset.

The overall NHANES response rate among adults aged 45 to 80 years between 2009 and 2014 was 67.9%. Patients were categorized as having impaired mobility if they responded “yes” to the following question: “Because of a health problem, do you have difficulty walking without using any special equipment?” Psoriasis status was assessed by the following question: “Have you ever been told by a doctor or other health professional that you had psoriasis?” Multivariable logistic regression analyses were performed using Stata/SE 18.0 software (StataCorp LLC) to assess the relationship between psoriasis and impaired mobility. Age, income, education, sex, race, tobacco use, diabetes status, body mass index, and arthritis status were controlled for in our models.

Our analysis initially included 9982 participants; 14 did not respond to questions assessing psoriasis and impaired mobility and were excluded. The prevalence of impaired mobility in patients with psoriasis was 17.1% compared with 10.9% among those without psoriasis (Table 1). There was a significant association between psoriasis and impaired mobility among patients aged 45 to 80 years after adjusting for potential confounding variables (adjusted odds ratio [AOR], 1.54; 95% CI, 1.04- 2.29; P=.032)(Table 2). Analyses of subgroups yielded no statistically significant results.

Our study demonstrated a statistically significant difference in mobility between individuals with psoriasis compared with the general population, which remained significant when controlling for arthritis, obesity, and diabetes (P=.032). This may be the result of several influences. First, the location of the psoriasis may impact mobility. Plantar psoriasis—a manifestation on the soles of the feet—can cause discomfort and pain, which can hinder walking and standing.⁵ Second, a study by Lasselin et al⁶ found that systemic inflammation contributes to mobility impairment through alterations in gait and posture, which suggests that the inflammatory processes inherent in psoriasis could intrinsically modify walking speed and stride, potentially exacerbating mobility difficulties independent of other comorbid conditions. These findings suggest that psoriasis may disproportionately affect individuals with impaired mobility, independent of comorbid arthritis, obesity, and diabetes.

These findings have broad implications for diversity, equity, and inclusion. They should prompt us to consider the practical challenges faced by this patient population and the ways that we can address barriers to care. Offering telehealth appointments, making primary care referrals for impaired mobility workups, and advising patients of direct-to-home delivery of prescriptions are good places to start.

Limitations to our study include the lack of specificity in the survey question, self-reporting bias, and the inability to control for the psoriasis location. Further investigations are warranted in large, representative US adult populations to assess the implications of impaired mobility in patients with psoriasis.

To the Editor:

UV light plays an essential role in various environmental and biological processes.¹ Excessive exposure to UV radiation can lead to sunburn, which is marked by skin erythema and pain.² A study of more than 31,000 individuals found that 34.2% of adults aged 18 years and older reported at least 1 sunburn during the survey year.³ A lack of research regarding the incidence of sunburns in patients with psoriasis is particularly important considering the heightened incidence of skin cancer observed in this population.⁴ Thus, the aim of our study was to analyze the prevalence of sunburns among US adults with psoriasis utilizing data from the National Health and Nutrition Examination Survey (NHANES) database.⁵

Our analysis initially included 11,842 participants ranging in age from 20 to 59 years; 35 did not respond to questions assessing psoriasis and sunburn prevalence and thus were excluded. Multivariable logistic regression analyses were performed using Stata/SE 18 (StataCorp LLC) to assess the relationship between psoriasis and sunburns. Our models controlled for patient age, sex, income, race, education, diabetes status, tobacco use, and body mass index. A P value <.05 was considered statistically significant. The study period from January 2009 to December 2014 was chosen based on the availability of the most recent and comprehensive psoriasis data within the NHANES database.

In the NHANES data we evaluated, psoriasis status was assessed by asking, “Have you ever been told by a doctor or other health professional that you had psoriasis?” History of sunburns in the survey year was assessed by the question, “How many times in the past year have you had sunburn?” Patients who reported 1 or more sunburns were included in the sunburn cohort, while those who did not report a sunburn were included in the no sunburn cohort.

In our analysis, the prevalence of at least 1 sunburn in the survey year in patients with psoriasis was 55.4% (weighted), compared to 45.6% (weighted) among those without psoriasis (eTable 1). Although there was no statistically significant relationship between psoriasis and history of sunburn in patients aged 20 to 59 years, a subgroup analysis revealed a significant association between psoriasis and sunburn in adults aged 20 to 39 years after adjusting for potential confounding variables (adjusted OR, 1.57 [95% CI, 1.00-2.45]; P=.049)(eTable 2). Further analysis of subgroups showed no statistically significant results with adjustment of the logistic regression model. Characterizing response rates is important for assessing the validity of survey studies. The NHANES response rate from 2009 to 2014 was 72.9%, enhancing the reliability of our findings.

Our study revealed an increased prevalence of sunburn in US adults with psoriasis. A trend of increased sunburn prevalence among younger adults regardless of psoriasis status is corroborated by the literature. Surveys conducted in the United States in 2005, 2010, and 2015 showed that 43% to 50% of adults aged 18 to 39 years and 28% to 42% of those aged 40 to 59 years reported experiencing at least 1 sunburn within the respective survey year.⁶ Furthermore, in our study, patients with psoriasis reported higher rates of sunburn than their counterparts without psoriasis, both in those aged 20 to 39 years (psoriasis, 62.8% [73/136]; no psoriasis, 51.1% [2425/5840]) and those aged 40 to 59 years (psoriasis, 50.5% [n=75/179]; no psoriasis, 40.2% [1613/5652]), though it was only statistically significant in the 20-to-39 age group. This discrepancy may be attributed to differences in sun-protective behaviors in younger vs older adults. A study from the NHANES database found that, among individuals aged 20 to 39 years, 75.9% [4225/5493] reported staying in the shade, 50.0% [2346/5493] reported using sunscreen, and 31.2% [1874/5493] reported wearing sun-protective clothing.⁷ Interestingly, the likelihood of engaging in all 3 behaviors was 28% lower in the 20-to-39 age group vs the 40-to-59 age group (adjusted OR, 0.72; 95% CI, 0.62-0.83).⁷

While our analysis adjusted for age, race/ethnicity, and tobacco use to mitigate potential confounding, we acknowledge the statistically significant differences observed in these variables between study groups as presented in eTable 2. These differences may reflect inherent disparities in the study population. We employed multivariable regression analysis to control for these covariates in our primary analyses. Of note, there was a statistically significant difference associated with race/ethnicity when comparing non-Hispanic White individuals with psoriasis (77.0% [n=182/315]) and those without psoriasis (62.5% [n=4516/11,492])(P<.0001)(eTable 1). The higher proportion of non-Hispanic White patients in the psoriasis group may reflect an increased susceptibility to sunburn given their typically lighter skin pigmentation; however, our analysis controlled for race/ethnicity (eTable 2), thereby allowing us to isolate the effect of psoriasis on sunburn prevalence independent of racial/ethnic differences. There also were statistically significant differences in tobacco use (P=.0026) and age (P=.002) in our unadjusted findings (eTable 1). Again, our analysis controlled for these factors (eTable 2), thereby allowing us to isolate the effect of psoriasis on sunburn prevalence independent of tobacco use and age differences. This approach enhanced the reliability of our findings.

The association between psoriasis and skin cancer has previously been evaluated using the NHANES database—one study found that patients with psoriasis had a significantly higher prevalence of nonmelanoma skin cancer compared with those without psoriasis (3.0% vs 1.3%; relative risk, 2.29; P<.001).⁸ This difference remained significant after adjusting for confounding variables, as it was found that psoriasis was independently associated with a 1.5-fold increased risk for nonmelanoma skin cancer (adjusted relative risk, 2.06; P=.004).⁸

The relationship between psoriasis and sunburn may be due to behavioral choices, such as the use of phototherapy for managing psoriasis due to its recognized advantages.⁹ Patients may seek out both artificial and natural light sources more frequently, potentially increasing the risk for sunburn.¹⁰ Psoriasis-related sunburn susceptibility may stem from biological factors, including vitamin D insufficiency, as vitamin D is crucial for keratinocyte differentiation, immune function, and UV protection and repair.¹¹ One study examined the effects of high-dose vitamin D3 on sunburn-induced inflammation.¹² Patients who received high-dose vitamin D3 exhibited reduced skin inflammation, enhanced skin barrier repair, and increased anti-inflammatory response compared with those who did not receive the supplement. This improvement was associated with upregulation of arginase 1, an anti-inflammatory enzyme, leading to decreased levels of pro-inflammatory mediators such as tumor necrosis factor α and inducible nitric oxide synthase, thereby promoting tissue repair and reducing prolonged inflammation.¹² These findings suggest that vitamin D insufficiency coupled with dysregulated immune responses may contribute to the heightened susceptibility of individuals with psoriasis to sunburn.

The established correlation between sunburn and skin cancer^4,8 coupled with our findings of increased prevalence of sunburn in individuals with psoriasis underscores the need for additional research to clarify the underlying biological and behavioral factors that may contribute to a higher prevalence of sunburn in these patients, along with the implications for skin cancer development. Limitations of our study included potential recall bias, as individuals self-reported their clinical conditions and the inability to incorporate psoriasis severity into our analysis, as this was not consistently captured in the NHANES questionnaire during the study period.

To the Editor:

UV light plays an essential role in various environmental and biological processes.¹ Excessive exposure to UV radiation can lead to sunburn, which is marked by skin erythema and pain.² A study of more than 31,000 individuals found that 34.2% of adults aged 18 years and older reported at least 1 sunburn during the survey year.³ A lack of research regarding the incidence of sunburns in patients with psoriasis is particularly important considering the heightened incidence of skin cancer observed in this population.⁴ Thus, the aim of our study was to analyze the prevalence of sunburns among US adults with psoriasis utilizing data from the National Health and Nutrition Examination Survey (NHANES) database.⁵

Our analysis initially included 11,842 participants ranging in age from 20 to 59 years; 35 did not respond to questions assessing psoriasis and sunburn prevalence and thus were excluded. Multivariable logistic regression analyses were performed using Stata/SE 18 (StataCorp LLC) to assess the relationship between psoriasis and sunburns. Our models controlled for patient age, sex, income, race, education, diabetes status, tobacco use, and body mass index. A P value <.05 was considered statistically significant. The study period from January 2009 to December 2014 was chosen based on the availability of the most recent and comprehensive psoriasis data within the NHANES database.

In the NHANES data we evaluated, psoriasis status was assessed by asking, “Have you ever been told by a doctor or other health professional that you had psoriasis?” History of sunburns in the survey year was assessed by the question, “How many times in the past year have you had sunburn?” Patients who reported 1 or more sunburns were included in the sunburn cohort, while those who did not report a sunburn were included in the no sunburn cohort.

In our analysis, the prevalence of at least 1 sunburn in the survey year in patients with psoriasis was 55.4% (weighted), compared to 45.6% (weighted) among those without psoriasis (eTable 1). Although there was no statistically significant relationship between psoriasis and history of sunburn in patients aged 20 to 59 years, a subgroup analysis revealed a significant association between psoriasis and sunburn in adults aged 20 to 39 years after adjusting for potential confounding variables (adjusted OR, 1.57 [95% CI, 1.00-2.45]; P=.049)(eTable 2). Further analysis of subgroups showed no statistically significant results with adjustment of the logistic regression model. Characterizing response rates is important for assessing the validity of survey studies. The NHANES response rate from 2009 to 2014 was 72.9%, enhancing the reliability of our findings.

Our study revealed an increased prevalence of sunburn in US adults with psoriasis. A trend of increased sunburn prevalence among younger adults regardless of psoriasis status is corroborated by the literature. Surveys conducted in the United States in 2005, 2010, and 2015 showed that 43% to 50% of adults aged 18 to 39 years and 28% to 42% of those aged 40 to 59 years reported experiencing at least 1 sunburn within the respective survey year.⁶ Furthermore, in our study, patients with psoriasis reported higher rates of sunburn than their counterparts without psoriasis, both in those aged 20 to 39 years (psoriasis, 62.8% [73/136]; no psoriasis, 51.1% [2425/5840]) and those aged 40 to 59 years (psoriasis, 50.5% [n=75/179]; no psoriasis, 40.2% [1613/5652]), though it was only statistically significant in the 20-to-39 age group. This discrepancy may be attributed to differences in sun-protective behaviors in younger vs older adults. A study from the NHANES database found that, among individuals aged 20 to 39 years, 75.9% [4225/5493] reported staying in the shade, 50.0% [2346/5493] reported using sunscreen, and 31.2% [1874/5493] reported wearing sun-protective clothing.⁷ Interestingly, the likelihood of engaging in all 3 behaviors was 28% lower in the 20-to-39 age group vs the 40-to-59 age group (adjusted OR, 0.72; 95% CI, 0.62-0.83).⁷

While our analysis adjusted for age, race/ethnicity, and tobacco use to mitigate potential confounding, we acknowledge the statistically significant differences observed in these variables between study groups as presented in eTable 2. These differences may reflect inherent disparities in the study population. We employed multivariable regression analysis to control for these covariates in our primary analyses. Of note, there was a statistically significant difference associated with race/ethnicity when comparing non-Hispanic White individuals with psoriasis (77.0% [n=182/315]) and those without psoriasis (62.5% [n=4516/11,492])(P<.0001)(eTable 1). The higher proportion of non-Hispanic White patients in the psoriasis group may reflect an increased susceptibility to sunburn given their typically lighter skin pigmentation; however, our analysis controlled for race/ethnicity (eTable 2), thereby allowing us to isolate the effect of psoriasis on sunburn prevalence independent of racial/ethnic differences. There also were statistically significant differences in tobacco use (P=.0026) and age (P=.002) in our unadjusted findings (eTable 1). Again, our analysis controlled for these factors (eTable 2), thereby allowing us to isolate the effect of psoriasis on sunburn prevalence independent of tobacco use and age differences. This approach enhanced the reliability of our findings.

The association between psoriasis and skin cancer has previously been evaluated using the NHANES database—one study found that patients with psoriasis had a significantly higher prevalence of nonmelanoma skin cancer compared with those without psoriasis (3.0% vs 1.3%; relative risk, 2.29; P<.001).⁸ This difference remained significant after adjusting for confounding variables, as it was found that psoriasis was independently associated with a 1.5-fold increased risk for nonmelanoma skin cancer (adjusted relative risk, 2.06; P=.004).⁸

The relationship between psoriasis and sunburn may be due to behavioral choices, such as the use of phototherapy for managing psoriasis due to its recognized advantages.⁹ Patients may seek out both artificial and natural light sources more frequently, potentially increasing the risk for sunburn.¹⁰ Psoriasis-related sunburn susceptibility may stem from biological factors, including vitamin D insufficiency, as vitamin D is crucial for keratinocyte differentiation, immune function, and UV protection and repair.¹¹ One study examined the effects of high-dose vitamin D3 on sunburn-induced inflammation.¹² Patients who received high-dose vitamin D3 exhibited reduced skin inflammation, enhanced skin barrier repair, and increased anti-inflammatory response compared with those who did not receive the supplement. This improvement was associated with upregulation of arginase 1, an anti-inflammatory enzyme, leading to decreased levels of pro-inflammatory mediators such as tumor necrosis factor α and inducible nitric oxide synthase, thereby promoting tissue repair and reducing prolonged inflammation.¹² These findings suggest that vitamin D insufficiency coupled with dysregulated immune responses may contribute to the heightened susceptibility of individuals with psoriasis to sunburn.

The established correlation between sunburn and skin cancer^4,8 coupled with our findings of increased prevalence of sunburn in individuals with psoriasis underscores the need for additional research to clarify the underlying biological and behavioral factors that may contribute to a higher prevalence of sunburn in these patients, along with the implications for skin cancer development. Limitations of our study included potential recall bias, as individuals self-reported their clinical conditions and the inability to incorporate psoriasis severity into our analysis, as this was not consistently captured in the NHANES questionnaire during the study period.

To the Editor:

UV light plays an essential role in various environmental and biological processes.¹ Excessive exposure to UV radiation can lead to sunburn, which is marked by skin erythema and pain.² A study of more than 31,000 individuals found that 34.2% of adults aged 18 years and older reported at least 1 sunburn during the survey year.³ A lack of research regarding the incidence of sunburns in patients with psoriasis is particularly important considering the heightened incidence of skin cancer observed in this population.⁴ Thus, the aim of our study was to analyze the prevalence of sunburns among US adults with psoriasis utilizing data from the National Health and Nutrition Examination Survey (NHANES) database.⁵

Our analysis initially included 11,842 participants ranging in age from 20 to 59 years; 35 did not respond to questions assessing psoriasis and sunburn prevalence and thus were excluded. Multivariable logistic regression analyses were performed using Stata/SE 18 (StataCorp LLC) to assess the relationship between psoriasis and sunburns. Our models controlled for patient age, sex, income, race, education, diabetes status, tobacco use, and body mass index. A P value <.05 was considered statistically significant. The study period from January 2009 to December 2014 was chosen based on the availability of the most recent and comprehensive psoriasis data within the NHANES database.

In the NHANES data we evaluated, psoriasis status was assessed by asking, “Have you ever been told by a doctor or other health professional that you had psoriasis?” History of sunburns in the survey year was assessed by the question, “How many times in the past year have you had sunburn?” Patients who reported 1 or more sunburns were included in the sunburn cohort, while those who did not report a sunburn were included in the no sunburn cohort.

In our analysis, the prevalence of at least 1 sunburn in the survey year in patients with psoriasis was 55.4% (weighted), compared to 45.6% (weighted) among those without psoriasis (eTable 1). Although there was no statistically significant relationship between psoriasis and history of sunburn in patients aged 20 to 59 years, a subgroup analysis revealed a significant association between psoriasis and sunburn in adults aged 20 to 39 years after adjusting for potential confounding variables (adjusted OR, 1.57 [95% CI, 1.00-2.45]; P=.049)(eTable 2). Further analysis of subgroups showed no statistically significant results with adjustment of the logistic regression model. Characterizing response rates is important for assessing the validity of survey studies. The NHANES response rate from 2009 to 2014 was 72.9%, enhancing the reliability of our findings.

Our study revealed an increased prevalence of sunburn in US adults with psoriasis. A trend of increased sunburn prevalence among younger adults regardless of psoriasis status is corroborated by the literature. Surveys conducted in the United States in 2005, 2010, and 2015 showed that 43% to 50% of adults aged 18 to 39 years and 28% to 42% of those aged 40 to 59 years reported experiencing at least 1 sunburn within the respective survey year.⁶ Furthermore, in our study, patients with psoriasis reported higher rates of sunburn than their counterparts without psoriasis, both in those aged 20 to 39 years (psoriasis, 62.8% [73/136]; no psoriasis, 51.1% [2425/5840]) and those aged 40 to 59 years (psoriasis, 50.5% [n=75/179]; no psoriasis, 40.2% [1613/5652]), though it was only statistically significant in the 20-to-39 age group. This discrepancy may be attributed to differences in sun-protective behaviors in younger vs older adults. A study from the NHANES database found that, among individuals aged 20 to 39 years, 75.9% [4225/5493] reported staying in the shade, 50.0% [2346/5493] reported using sunscreen, and 31.2% [1874/5493] reported wearing sun-protective clothing.⁷ Interestingly, the likelihood of engaging in all 3 behaviors was 28% lower in the 20-to-39 age group vs the 40-to-59 age group (adjusted OR, 0.72; 95% CI, 0.62-0.83).⁷

While our analysis adjusted for age, race/ethnicity, and tobacco use to mitigate potential confounding, we acknowledge the statistically significant differences observed in these variables between study groups as presented in eTable 2. These differences may reflect inherent disparities in the study population. We employed multivariable regression analysis to control for these covariates in our primary analyses. Of note, there was a statistically significant difference associated with race/ethnicity when comparing non-Hispanic White individuals with psoriasis (77.0% [n=182/315]) and those without psoriasis (62.5% [n=4516/11,492])(P<.0001)(eTable 1). The higher proportion of non-Hispanic White patients in the psoriasis group may reflect an increased susceptibility to sunburn given their typically lighter skin pigmentation; however, our analysis controlled for race/ethnicity (eTable 2), thereby allowing us to isolate the effect of psoriasis on sunburn prevalence independent of racial/ethnic differences. There also were statistically significant differences in tobacco use (P=.0026) and age (P=.002) in our unadjusted findings (eTable 1). Again, our analysis controlled for these factors (eTable 2), thereby allowing us to isolate the effect of psoriasis on sunburn prevalence independent of tobacco use and age differences. This approach enhanced the reliability of our findings.

The association between psoriasis and skin cancer has previously been evaluated using the NHANES database—one study found that patients with psoriasis had a significantly higher prevalence of nonmelanoma skin cancer compared with those without psoriasis (3.0% vs 1.3%; relative risk, 2.29; P<.001).⁸ This difference remained significant after adjusting for confounding variables, as it was found that psoriasis was independently associated with a 1.5-fold increased risk for nonmelanoma skin cancer (adjusted relative risk, 2.06; P=.004).⁸

The relationship between psoriasis and sunburn may be due to behavioral choices, such as the use of phototherapy for managing psoriasis due to its recognized advantages.⁹ Patients may seek out both artificial and natural light sources more frequently, potentially increasing the risk for sunburn.¹⁰ Psoriasis-related sunburn susceptibility may stem from biological factors, including vitamin D insufficiency, as vitamin D is crucial for keratinocyte differentiation, immune function, and UV protection and repair.¹¹ One study examined the effects of high-dose vitamin D3 on sunburn-induced inflammation.¹² Patients who received high-dose vitamin D3 exhibited reduced skin inflammation, enhanced skin barrier repair, and increased anti-inflammatory response compared with those who did not receive the supplement. This improvement was associated with upregulation of arginase 1, an anti-inflammatory enzyme, leading to decreased levels of pro-inflammatory mediators such as tumor necrosis factor α and inducible nitric oxide synthase, thereby promoting tissue repair and reducing prolonged inflammation.¹² These findings suggest that vitamin D insufficiency coupled with dysregulated immune responses may contribute to the heightened susceptibility of individuals with psoriasis to sunburn.

The established correlation between sunburn and skin cancer^4,8 coupled with our findings of increased prevalence of sunburn in individuals with psoriasis underscores the need for additional research to clarify the underlying biological and behavioral factors that may contribute to a higher prevalence of sunburn in these patients, along with the implications for skin cancer development. Limitations of our study included potential recall bias, as individuals self-reported their clinical conditions and the inability to incorporate psoriasis severity into our analysis, as this was not consistently captured in the NHANES questionnaire during the study period.