Psoriasis is a chronic inflammatory skin disease and presents as erythematous plaques with silvery scales. It also commonly affects the joints and nails and exhibits systemic manifestations.¹⁾ Some comorbidities have been associated with psoriasis, including metabolic syndrome and depression, and the condition significantly affects patient quality of life.²⁾

Psoriasis affects approximately 2%–4% of the population in Europe and the United States, whereas the prevalence in Asian countries is lower.³⁾ The prevalence ranges from 0.29% to 1.18% in Japan and 0.2% to 1.5% in China. In Korea, the prevalence is 453 per 100,000 population.⁴⁾ The age of onset of psoriasis shows a bimodal distribution, with the first peak occurring at 15–25 or 30–39 years and the second at 50–70 years.^3,5) A population-based study in the United States observed the highest rate of psoriasis incidence among patients aged 60–69 years.¹⁾ With ongoing increases in aging populations, psoriasis in older patients is also expected to increase. Aside from the comorbidities, this population is also more vulnerable to the psychological distress and impaired quality of life that are associated with psoriasis.⁶⁾ Most skin diseases in older patients are treatable if detected early; thus, physicians must be attentive when presented with patients from this specific population,⁷⁾ as early and late-onset psoriasis have clinical differences and distinct characteristics in geriatric patients.^5,6,8,9)

Although the demographic and clinical characteristics of patients with psoriasis have been evaluated in many countries, studies specifically on geriatric patients remain scarce and none have focused on patients receiving phototherapy, who generally have moderate-to-severe psoriasis.^4,5,9-15) Obtaining this information may provide a better understanding of the psoriasis characteristics in this population and help clinicians make appropriate decisions. Phototherapy is a good alternative to systemic therapy, especially for older patients with polypharmacy, and has long been utilized with great efficacy and safety for many dermatoses. Therefore, this study aimed to describe the sociodemographic and clinical characteristics of geriatric patients with psoriasis in Indonesia, specifically those who received narrowband ultraviolet B (NB-UVB) phototherapy.

This study was conducted at the Dermatovenereology Clinic of Dr. Cipto Mangunkusumo National General Hospital. Data were obtained from the phototherapy and medical records of geriatric patients with psoriasis who received phototherapy between 2014 and 2019. The inclusion criterion was all psoriasis patients aged ≥60 years who received NB-UVB phototherapy between January 2014 and August 2019. Patients were excluded if they had undergone fewer than eight phototherapy sessions or if the information in the medical records was incomplete. The study has been approved by the Health Research Ethics Committee (No. 0981/UN2.F1/ETIK/2018), Faculty of Medicine, Universitas Indonesia, and Dr. Cipto Mangunkusumo National General Hospital. Informed consent for phototherapy was obtained before treatment.

This study included a total of 24 patients with psoriasis who received NB-UVB phototherapy. Their sociodemographic data are summarized (Table 1). All patients were diagnosed as having plaque-type psoriasis; however, 2 patients also had guttate psoriasis and 2 patients had pustular psoriasis during phototherapy.

According to the Asia-Pacific-specific classification of body mass index (BMI), the median BMI of all patients was classified as overweight (BMI 23.0–24.9 kg/m²; median, 24.7 kg/m²; range, 18.8-37.0 kg/m²), whereas 11 patients (45.8%) were obese. Among 15 patients with available lipid profile data, 12 had low-density lipoprotein (LDL) levels above 100 mg/dL, 4 had total cholesterol levels above 200 mg/dL, 2 male patients had high-density lipoprotein (HDL) levels below 40 mg/dL, one female patient had an HDL level below 50 mg/dL, and 3 patients had triglyceride levels above 150 mg/dL. The majority of educational level in our study was bachelor and master graduates (41.7%). The patients’ baseline characteristics are summarized in Table 1.

Regarding comorbidities, dyslipidemia (n=15; 62.5%) and hypertension (n=15; 62.5%) were the most common in these patients (Table 2).

Medications that are reported to have photosensitizing properties were consumed by 11 patients during their phototherapy course, with 4 patients consuming multiple photosensitizing medications. The medications were statins (n=7; 29.2%); methotrexate (n=2; 8.3%); non-steroidal anti-inflammatory drugs (NSAIDs; n=3; 12.5%); and nifedipine, captopril, furosemide, hydrochlorothiazide (n=1 in each; 4.2%). Two patients experienced one episode of side effects while consuming photosensitizing medications. However, no changes were made to their medications, only adjustment of phototherapy doses (Table 3).

We only included patients who received phototherapy, the treatment of choice for moderate-to-severe psoriasis. The present study did not include patients with mild disease severity. Thirteen patients achieved a PASI 75 response after a median of 19 sessions (range, 12–84) and a median cumulative dose of 24.8 J/cm² (range, 13.3–190.2 J/cm²). Seven patients were lost to follow-up; thus, treatment response could not be assessed. Three patients did not achieve improvement; therefore, their treatment was changed to a different modality.

This study was conducted to identify the demographic and clinical characteristics of geriatric patients with psoriasis treated with NB-UVB phototherapy. Our results showed a male predominance among the 24 included patients, with a male-to-female ratio of 2:1. Most studies reported no significant difference in prevalence across sex. However, other studies, particularly those conducted in Asian populations, reported a slightly higher prevalence in males, although the ratio was not as high as in our study.^{2,4,10,12,15)} Furthermore, a study in Taiwan reported an increasing prevalence of psoriasis in men by the age of 30 years.¹⁵⁾

The most common educational level in our study was bachelor and master graduates, in contrast to another epidemiological study conducted in our hospital for vitiligo patients, in which most of the patients were elementary/middle/high school graduates.¹⁶⁾ Epidemiological studies conducted in the United States also revealed that only 38% of the patients were college graduates,¹⁴⁾ whereas those conducted in Africa reported that 72.3% of the cases had primary and secondary education.¹¹⁾ The higher educational level observed in our patients might be of advantage when providing information to patients regarding their treatments, complications, and disease course.

Concerning the age of onset, the median was 61 years (range, 36–74 years). This is consistent with the reported bimodal distribution of the age of onset for psoriasis, in which the second peak occurs around 50–70 years of age.³⁾ A study comparing the clinical characteristics of psoriasis patients aged under and over 70 years also reported that patients aged ≥70 years had late-onset disease, occurring at 55.7±20.8 years, compared with patients aged under 70 years, in whom disease onset occurred at 28.6±15.0 years.⁵⁾ This finding is similar to ours, in which the mean age at onset was 59.77±10.06 years. As our study only included geriatric patients, most were categorized as having late-onset psoriasis (>40 years of age).

All of our patients were diagnosed as having plaque-type psoriasis, consistent with previous studies reporting the plaque-type to be the most common type of psoriasis.^4,5,9-15) The number of patients with other psoriasis types was too small for us to draw any conclusion. Nonetheless, a study in France observed a higher frequency of guttate and inverse psoriasis among patients aged >70 years,⁵⁾ whereas a study in Côte d'Ivoire demonstrated an increasing tendency for pustular and inverse psoriasis among patients with elderly-onset psoriasis.¹¹⁾

Compared with early onset psoriasis, late-onset psoriasis generally has a milder disease severity.^5,9) However, as we only included patients who received phototherapy, which is the treatment of choice for moderate-to-severe psoriasis, none of our patients had mild disease severity at baseline. Moreover, 83.3% of our patients had previously received treatment for psoriasis, including topical agents, immunosuppressive agents, or phototherapy. Most of those patients were treated in other hospitals and then referred to Dr. Cipto Mangunkusumo National General Hospital because of unsatisfactory improvement or even worsening course of the disease. This finding was consistent with moderate-to-severe disease severity and a long duration of psoriasis at baseline, with a median of 3 years (range from 2 months to 31 years).

In our study, 54.2% of patients achieved a PASI 75 response. The patients underwent a median of 19 sessions, with a median cumulative dose of 24.8 J/cm². Yones et al.¹⁷⁾ reported that 65% of psoriasis patients achieved PASI 75 over a median of 28.5 sessions, whereas Markham et al.¹⁸⁾ showed a clear response in psoriasis after 25.5 sessions. The treatment response of our study might be lower because of the lower median number of sessions.

In this study, almost half of the patients were obese (45.8%), and the median BMI was classified as overweight. More than half of the patients were hypertensive and had dyslipidemia. Furthermore, 37.5% of patients were on treatment for diabetes and 25% had been diagnosed with hyperuricemia. Previous studies have demonstrated a significantly increased risk of metabolic syndrome—which includes obesity, diabetes mellitus, hypertension, dyslipidemia, and cardiovascular disorder—in psoriasis patients.^{2,4,10,12,19,20)} This increased occurrence of metabolic syndrome remained significant after adjusting for age, sex, race/ethnicity, smoking, and C-reactive protein levels and was also correlated positively with the psoriasis severity.¹⁷⁾ Several studies have also reported an increased prevalence of nonalcoholic steatohepatitis among psoriasis patients, which we observed in 2 patients in the present study.^2,8) Mallbris et al.²¹⁾ reported a significant increase in LDL and apolipoprotein A-1 levels and a change in the cholesterol/triglyceride ratio in patients with psoriasis for less than 1 year compared to those in healthy controls. Psoriasis is a chronic inflammatory systemic disease mediated by various inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), adiponectin, leptin, and plasminogen activator inhibitor-1 (PAI-1), which play important roles in both psoriasis and metabolic syndrome.¹⁹⁾ A review by Takahashi and Iizuka¹⁹⁾ described the role of adiponectin, which is an adipocyte-specific secretory protein. Levels of adiponectin are decreased in obesity, insulin resistance, type 2 diabetes mellitus, and coronary artery disease. Moreover, low adiponectin levels showed increased risk towards the development of diabetes, hypertension, and dyslipidemia. Moreover, psoriasis patients with normal weight show decreased levels of adiponectin compared to healthy controls with normal weight. A study in Japanese reported low adiponectin levels in psoriasis patients, which was negatively correlated with psoriasis severity, blood TNF-α, and interleukin (IL)-6 levels. Angiotensin-converting enzyme (ACE) and renin activity are also reportedly increased in psoriasis patients,¹⁹⁾ which explains the significantly higher prevalence of hypertension among psoriasis patients compared to that in patients with other dermatological diseases. Given the serious consequences for the coexistence of both psoriasis and metabolic syndrome, all patients diagnosed with psoriasis should be screened for metabolic syndrome. Additionally, Takeshita et al.²⁾ found that hypertension tended to be more severe and poorly controlled in psoriasis patients compared with patients without psoriasis. A meta-analysis also found a significantly greater reduction in PASI score among patients undergoing weight loss intervention than among those who did not.²⁾ Given that risk of comorbidities correlates positively with disease severity, the importance of compliance to both psoriasis and metabolic syndrome therapy needs to be emphasized to patients.

Besides metabolic syndrome, gingivitis/periodontitis was another prevalent comorbidity in our study. Previous studies have demonstrated an increased risk and incidence of periodontitis and gingivitis among psoriasis patients.^22,23) Another study also reported a higher incidence of psoriasis among patients with periodontitis.²⁴⁾ Furthermore, the number of comorbidities was higher in psoriasis or psoriatic arthritis patients who also had periodontitis.²³⁾ Further, patients with psoriatic arthritis or more severe psoriasis severity had more severe periodontitis.²²⁾ Although smoking is believed to be an important confounding factor for periodontitis, Egeberg et al.²³⁾ found that the risk of periodontitis persisted after adjusting for smoking. Unfortunately, we did not have data on the smoking behavior of our patients. The association between psoriasis and periodontitis was linked by the similarities in their underlying inflammatory and immunological processes. IL-17A is a crucial player in the pathogenesis of both diseases.^22,23) The bacterial microenvironment in periodontitis, which is dominated by Porphyromonas gingivalis, is believed to induce the production of IL-17A, a pro-inflammatory cytokine involved in tissue destruction and osteoclastogenesis.^23,25) P. gingivalis drives chronic inflammatory and tissue destruction processes and enters systemic circulation, on the basis of its detection at distant sites. Its antibodies were also present in the synovial fluid of patients with rheumatic arthritis and atheromas.²⁵⁾ Additionally, psoriasis patients had lower concentration and secretion rates of salivary immunoglobulin A (IgA) and lysozyme, which are important parts of the oral mucosal defense system, leading to an increased risk of oral infections.²⁶⁾ These findings emphasize the need for all psoriasis patients to undergo regular dental evaluations and receive education on how to maintain their oral health.

Consistent with the patients’ comorbidities, besides antihistamines, the most common systemic medications consumed by the patients were antihypertensive drugs and statins. Some of our patients consumed photosensitizing medications, including statins, methotrexate, NSAIDs, nifedipine, captopril, furosemide, and hydrochlorothiazide. Polypharmacy in geriatric patients might result in major problems because of degenerative changes that can affect drug pharmacokinetics and pharmacodynamics. Both adverse drug reactions and the risk of drug-drug interactions can be magnified.²⁷⁾ Thus, clinicians need to obtain detailed drug history and patients need to report any medication changes during their therapy. Furthermore, patients who take medications with photosensitizing properties need to be informed about the increased risk of side effects from phototherapy.

Another factor that should be considered is the exposure to certain medications that could elicit the induction of psoriasis. Beta-blockers, one of the antihypertensive drugs consumed by the patients in our study, are strongly associated with psoriasis. A prospective cohort study by Wu et al.²⁸⁾ found that beta-blockers were associated with an increased risk of psoriasis after regular use for 6 years or more. The pathogenesis by which beta-blockers provoke psoriasis is associated with the blockade of beta-adrenergic receptors.²⁹⁾ Moreover, the association between hypertension and psoriasis is likely induced by beta-blockers.²⁸⁾ In addition to beta-blockers, Cohen et al.³⁰⁾ found that calcium channel blocker (CCB) was associated with the precipitation of new-onset psoriasis. Furthermore, CCB was also associated with the exacerbation of psoriasis.³⁰⁾ However, the patients in the previous studies did not receive NB-UVB phototherapy for their psoriasis. In the current study, about 50% of our patients took beta-blockers and CCB. Unfortunately, their medical record did not document whether psoriasis had occurred after consuming beta-blockers or data on CCB.

The limitation of this study is its retrospective study design because of which some data are incomplete. In addition, the sample size was very small, which may not be representative of the general population and not comparable to the outcomes of other studies. We had tried to increase the number of patients in our study. However, we had difficulties to access the data as it becomes limited and restricted. Hence, we were unable to review the distribution of comorbidities in older patients with diseases other than psoriasis. In addition, we did not assess the characteristics of patients with milder disease severity for comparison, and we lacked data on patient quality of life, which is commonly implicated in geriatric patients. The advantages of this study are that few other studies have evaluated the sociodemographic and clinical characteristics of geriatric patients with skin diseases and this is the first study conducted specifically on patients receiving NB-UVB phototherapy, which is commonly administered to patients with higher severe disease severity.

In conclusion, this study evaluated the sociodemographic and clinical characteristics of geriatric patients with psoriasis treated with NB-UVB phototherapy. Psoriasis is associated with comorbidities including metabolic syndrome and periodontitis, which warrant increased clinician vigilance in the screening and evaluation of these diseases. The data from this study could help physicians to evaluate and make appropriate clinical decisions when managing psoriasis patients in this age group.