Introduction
Psoriatic arthritis (PsA) is a chronic, debilitating, inflammatory disease. The domains of PsA have been defined by the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) as peripheral arthritis, axial disease, enthesitis, dactylitis, psoriasis (PsO), and nail disease [
1]. More recently, the GRAPPA and Outcome Measures in Rheumatology (OMERACT) working group defined a core domain set including pain, Patient’s Global Assessment of disease activity, physical function, health-related quality of life (HRQoL), fatigue, and systemic inflammation, in addition to musculoskeletal and skin disease [
2,
3], reflecting the growing significance of patient-reported outcomes (PROs) for monitoring disease progression and treatment response. Indeed, in the Multinational Assessment of Psoriasis and Psoriatic Arthritis (MAPP) population-based survey, 88% of patients with PsA reported current joint pain or soreness, and 53% rated their disease as severe [
4].
Due to the complexity and range of symptoms involved, PsA may be diagnosed and managed by both dermatologists and rheumatologists. However, as PsA is often misdiagnosed or undiagnosed [
5,
6], estimates of its prevalence vary widely (ranging from 0.2 to 1.0% in the US [
7,
8] and from 0.1 to 2.0% in Europe [
9‐
13]) and is likely higher than reported [
14]. In addition, the proportion of patients suffering from both PsO and PsA has been estimated to range from 6 to 42% [
5,
6,
14‐
17].
PsA is associated with considerable disease burden, increased healthcare costs, and impairments in HRQoL and work productivity [
4,
18‐
20], and is associated with substantial comorbidities and extra-articular manifestations.
PsO and rheumatoid arthritis (RA), unique conditions that share symptoms with PsA, are associated with a number of comorbidities including increased risk of cardiovascular events and disease, mortality, infections, and malignancies compared with the general population [
21‐
29]. Patients with PsO also have higher levels of anxiety and depression, with the risk of these comorbidities further increased when suffering from both PsO and PsA [
30,
31].
Treatment guidelines from GRAPPA [
1], the American Academy of Dermatology (AAD) [
32], and the European League Against Rheumatism (EULAR) [
33] specify that treatment for PsA should reflect disease characteristics and response to prior treatment. Indeed, treatment should be initiated upon diagnosis by a dermatologist or rheumatologist with the goals of alleviating signs and symptoms, improving functional status, inhibiting structural damage, and improving HRQoL parameters [
1,
32,
33]. Furthermore, the treatment target should be remission or, where appropriate, minimal/low disease, with treatment decisions reflecting shared decision-making between patient and physician considering all attributes of the disease and treatment [
1,
32,
33].
EULAR guidelines recommend that patients with active PsA receive non-steroidal anti-inflammatory drugs (NSAIDs), then conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) if they do not respond to NSAIDs, followed by a biologic DMARD (usually starting with a tumor necrosis factor inhibitor [TNFi]) or targeted synthetic DMARD (such as the phosphodiesterase 4-inhibitor [PDE-4i], apremilast) if needed [
33]. AAD guidelines recommend methotrexate, TNFi, or a combination of both as first-line treatment in moderate or severe PsA [
32]. Non-pharmacologic strategies, such as patient education, exercise, and weight reduction, may also be used to manage the disease [
33].
Despite the development of treatment guidelines by GRAPPA, AAD, and EULAR, along with a greater understanding of the disease burden of PsA, the effects of real-world treatment patterns on PROs and health status have not been fully evaluated to date. Here, we report a descriptive, exploratory analysis of data from the cross-sectional, 2016 National Health and Wellness Survey (NHWS). The objectives of this analysis were to characterize patients with self-reported PsA and to describe the effect of treatment patterns (current treatment, or lack of treatment) on PROs, with the aim of improving understanding of how treatment affects health status in the real world in the US and EU5.
Discussion
In this cross-sectional, descriptive, exploratory analysis of 2016 NHWS PRO survey data, 1.17% of survey respondents in the US and 1.35% of respondents in the EU5 self-reported having PsA. This is higher than the mean reported adult population prevalence estimates of 0.19% in the UK [
12] and 1% in the US [
8]; however, estimates are variable and the estimated prevalence in this study is consistent with the upper ranges found in the literature. In addition, this difference may be a reflection of respondents who consider themselves to have PsA, but might actually have some form of musculoskeletal disorder alongside PsO or skin manifestation.
These data provide insight into current treatment patterns in the US and EU5, reporting that 62% and 64% of patients with PsA, respectively, self-reported receiving no treatment. However, as previously noted, as PsA was self-reported and no clinical diagnosis was given in this study, it is possible that patients self-reporting PsA may have suffered from PsO or a skin manifestation alongside a musculoskeletal disorder and these participants may have been disproportionally represented in the no treatment group. Despite this, the results were consistent with the findings of another study of PsA impact and unmet treatment needs in North America and Europe, in which 58% of patients self-reporting PsA when responding to a telephone survey reported receiving no treatment or topical therapy only [
4,
9]. In this analysis, the majority of patients in the US and EU5 receiving no treatment considered themselves to have mild or moderate disease (91.1 and 93.8%, respectively) and had the lowest Charlson Comorbidity index score amongst the treatment groups.
Prior to treatment, the majority of patients reported moderate or severe PsA (US: 81.0–92.7%, EU5: 82.2–92.5%). For patients receiving treatment with either advanced or other therapies, fewer patients self-reported severe disease (US: 7.4 and 3.1%; EU5: 13.6 and 11.2%, respectively), and a higher proportion reported mild disease (US: 45.3 and 59.2%, respectively; EU5: 42.4 and 41.1%, respectively), compared with self-reported pre-treatment severity, suggesting that patients responded to treatment. Despite this improvement, 54.7 and 40.8% of patients in the US and 57.6 and 58.9% of patients in the EU5 still rated their PsA as moderate or severe for advanced and other therapies, respectively.
This was a population-based survey relying on self-reported PsA rather than a study conducted in rheumatology or dermatology clinics. This likely impacted the patient population identified, resulting in a larger number of patients with lower disease activity, and therefore, a lower proportion of patients receiving advanced therapies and a higher proportion of patients receiving no treatment than might be expected. Despite this, both age distribution and the proportions of female/male patients were similar across the US and EU5 treatment groups. The largest proportion of patients in the US with a high BMI received other therapies, whereas in the EU5, the largest proportion of patients with a high BMI received advanced therapies. In addition, in both the US and EU5, patients receiving advanced therapies had the highest age-adjusted Charlson Comorbidity Index score compared with other treatment groups. These data indicate that high BMI and comorbidities are common in PsA, with the highest disease burden being observed in patients receiving advanced therapies.
The findings of these analyses confirmed the impact of PsA on HRQoL, with SF-36 PCS and MCS scores below the normative values seen in the general population [
40]. SF-36 PCS scores were similar to those reported in a literature review of studies of patients with PsA, while SF-36 MCS scores were low compared with those reported in the same review [
41]. The negative impact on the physical dimension of HRQoL is not unexpected considering the pain and swelling of joints often experienced by patients with PsA. Low SF-36 MCS scores likely reflect the well-documented impact of PsO and RA on HRQoL [
42‐
46]; many patients experience psychosocial problems and emotional distress due to the unsightly appearance of the skin lesions [
43].
The majority of US patients were in full-time employment and a greater proportion of these patients received advanced therapies compared with other treatment groups. In EU5, full-time employment levels were similar across treatment groups. Similar to the previous investigations in PsA [
4,
47], productivity was reported to have been impaired in patients self-reporting PsA in this survey. These findings are consistent with those in an NHWS 2010–2013 population-based survey in the same five European countries as the current study, in which overall work impairment was 52% [
47]. Similarly, in the MAPP population-based survey, 32% of patients with PsA reported missing work in the previous 12 months because of their PsA, and 32% reported that PsA had impacted their ability to work full time, although the extent of the work missed was not quantified [
4]. Work missed by patients with PsA in an international clinical trial of certolizumab pegol was lower than in the current study, ranging from 5 to 9% across treatment groups at baseline [
48]. Finally, activity impairment was slightly higher in patients receiving advanced therapies than those receiving other therapies or no treatment; this could be related to the higher disease severity reported by these patients.
Self-reported medication adherence was generally poor in the current study. This may be a reflection of access to advanced therapies in the EU5, with public insurance coverage being more prominent compared with the US healthcare systems. A recent systematic review of medication adherence in patients with a range of conditions, including PsA, identified varying levels of non-adherence, which can impact negatively on health outcomes and have associated economic costs [
49]. In the systematic review, psychosocial factors, such as perceived treatment efficacy and safety, emotional well-being, HCP–patient relationship, and practical barriers, were shown to be key factors in determining patient adherence to treatment, while demographic and clinical factors showed less of an association with adherence [
49]. Since reason for non-adherence was not explored in the current study, it is possible that some of the factors identified by Vangeli et al. influenced patients’ decisions regarding medication adherence [
49]. It is also possible that in the US, insurance coverage for advanced therapies is likely a negative factor impacting adherence.
A number of limitations of this analysis must be acknowledged. Patients were included if they selected PsA in response to the question ‘Which of the following conditions have you ever experienced?’, where PsA was listed under ‘chronic pain conditions’. The diagnosis of PsA was not further validated by physician or chart review. Grouping of patients by treatment was based on self-reports of treatments used to treat arthritis; it is, therefore, possible that some patients might have been receiving treatment for PsO that might also be effective for PsA, but would not necessarily have been captured. Disease severity (mild, moderate, or severe) was not defined and was determined based on a patient’s response to the question ‘What is the level of severity of your condition?’, with no criteria provided to guide self-rating of severity of PsA. Results may, therefore, differ from those that would have been obtained if respondents had been required to receive a formal physician-reported PsA diagnosis and severity rating. It is worth noting, however, that participants receiving advanced therapies and other therapies reported seeing a rheumatologist or dermatologist more frequently than those participants receiving no treatment, lending support to the self-reported PsA in these treatment groups. Patients were not required to be under the care of a clinician for their PsA, which might have resulted in different treatment patterns, with fewer patients being treated, particularly with advanced therapies, compared with patients under the care of a rheumatologist or dermatologist. Pre-treatment severity levels were based on patients’ recollection of their health state before they started treatment. Information regarding the delay between a patient starting their current treatment and responding to the survey was not collected in the survey. In addition, given the design of the survey questionnaire, it was not possible to analyze the influence of the various symptoms and comorbidities of PsA on the treatment received or the patients’ perception of disease severity. Selection bias may have affected these analyses; patients who are satisfied with their treatment are less likely to respond to these types of questionnaires, so this type of survey may select for patients who are unhappy with their treatment. Only patients with PsA who completed the arthritis module of the NHWS and provided information on treatment were included in the analysis; 9% and 13% of US and EU5 respondents, respectively, with self-reported PsA were excluded from the analysis because of missing data. Data were limited to those obtained from patients who volunteered to participate, and therefore, results may not be applicable to the entire PsA population. Although this study included patients from the US and five European countries, it may not reflect clinical experience in all countries. Finally, although adherence was recorded, reasons for lack of adherence were not recorded, and it is possible that adherence was lower in patients who felt their treatments did not work or were too expensive. In addition, results here were not adjusted by age or gender, which may limit their interpretation.
Finally, although disease severity in patients receiving advanced and other therapies was reported to have changed after initiating treatment, 40–60% of patients reported moderate-to-severe PsA while being treated. The findings underscore the need for overall better management and identification of PsA, which, as demonstrated in this study, has a substantial impact on patients’ mental and physical health, employment, and healthcare resource utilization. Key areas for improvement include the early recognition of the disease and utilization of the guideline recommendation of a shared decision-making process between patient and physician on a treatment strategy to achieve remission or, alternatively, low disease activity as a treatment goal.
Compliance with ethical standards
Conflict of interest
A Gottlieb is a consultant/advisory board member and is a member of the speakers’ bureaus for AbbVie, Allergan, Beiersdorf Inc., Bristol-Myers Squibb, Celgene Corp, Dermira, Incyte, Janssen, Lilly, Novartis, Reddy Labs, Sun Pharmaceutical Industries, UCB, Valeant, and XBiotech, and has received research/educational grants from Incyte, Janssen, Lilly, Novartis and UCB. J Gratacos has received consulting fees or other remuneration from AbbVie, Celgene, Janssen-Cilag, MSD, Novartis, Pfizer Inc, and UCB. A Dikranian has received consulting fees or other remuneration from, and has held non-remunerative positions of influence with, AbbVie and Pfizer Inc, is a member of an advisory board for Novartis and Pfizer Inc, and is a member of the speakers’ bureaus for AbbVie, Amgen, Bristol-Myers Squibb, Celgene, Mallinckrodt, Novartis, and Pfizer Inc. A van Tubergen has received grants, research, or clinical trial support from AbbVie, Celgene, Janssen-Cilag, MSD, Novartis, Pfizer Inc, and UCB, is a member of the speakers’ bureaus for Janssen-Cilag, MSD, and Pfizer Inc, and is a consultant or member of an advisory board for Janssen-Cilag, Novartis, and Pfizer Inc. L Fallon, B Emir, L Aikman, and T Smith are shareholders and employees of Pfizer Inc. L Aikman is a shareholder of Pfizer Inc and former employee of Pfizer UK. L Chen is a shareholder and former employee of Pfizer Inc.