Department of Rheumatology, Nuffield Orthopaedic Centre, Oxford, 1 Department of Dermatology, Churchill Hospital, Oxford and 2 ICRF/NHS Centre for Statistics in Medicine, Institute of Health Sciences, Oxford, UK.
Correspondence to: L. Williamson, The Great Western Hospital, Swindon SN1 4JU, UK. E-mail: lyn.williamson{at}smnhst.swest.nhs.uk
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Abstract |
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Methods. We studied 69 patients with PsA at two visits. On the first visit, a rheumatology assessment of joint, skin and nail disease was made. On the second visit, a detailed dermatology assessment of skin and nails was made. Nail disease was analysed using a 20-nail psoriasis nail severity score (PNSS).
Results..There were 57 (83%) patients with clinical evidence of psoriatic nail disease. Although 66 (96%) patients had been treated for skin disease, only one (1%) had received any treatment for nail disease. Severe nail disease measured by the PNSS correlated with severe skin psoriasis as indicated by the percentage of body surface area affected by psoriasis (r = 0.34, P = 0.004) and physician global assessment of psoriasis (r = 0.45, P<0.001). Patients with distal interphalangeal (DIP) joint disease had higher PNSS scores (P = 0.03). The PNSS was also associated with unremitting and progressive arthritis (P<0.001), and correlated with Stanford health assessment questionnaire (HAQ) (r = 0.34, P = 0.004), depression (r = 0.39, P<0.001) and anxiety (r = 0.34, P = 0.004) scores. Compared with dermatology assessment, the rheumatology examination of nail disease had a positive predictive value of 84% and negative predictive value of 83%.
Conclusions. In patients with PsA, the severity of nail disease correlates with indicators of severity of both skin and joint disease. Although rheumatologists can adequately screen for nail disease, the management of this aspect of PsA is often overlooked.
KEY WORDS: Psoriatic arthritis, Nail disease.
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Introduction |
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Nail disease has been shown to be associated with functional impairment in patients with psoriasis [8]. In addition, the psychological distress caused by hand problems in patients with arthritis has been recognized [9]. Although there have been a number of advances in the treatment of psoriatic nail disease [1015], it is uncertain whether these therapies have been widely adopted in clinical practice.
Our aim was to make a comprehensive study of nail disease in a group of PsA patients, and to assess the relationship between nail, skin and joint disease. We also wished to assess the practical management of nail disease, including detection and current treatments of this problem.
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Methods |
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Patients were considered to have PsA if they had inflammatory arthritis and psoriasis; those with a rheumatoid factor titre of >1:160 or reactive arthritis with a clear infective trigger were excluded. Of 149 patients invited, 103 were eventually recruited to the study (41 declined to take part, 2 had rheumatoid arthritis, 1 had reactive arthritis and 2 had never had psoriasis). The clinical characteristics of this group have been reported previously [16].
On the first study visit a rheumatologist (LW or JD) assessed all patients. A careful history was taken about the pattern of their skin psoriasis and nail disease. Patients were questioned directly about a history of enthesitis, dactylitis and inflammatory back pain. Skin, nails and joints and spine were examined. A diagnosis of enthesitis was accepted if there was a history of inflammatory pain at an entheseal site or clinical evidence of enthesitis on examination. Dactylitis was diagnosed by a typical history or on clinical examination. Axial disease was defined by the presence of a history of inflammatory back or neck pain and/or reduced cervical, thoracic or lumbar movements [16]. The progression of arthritis was documented as episodic with complete resolution, episodic with incomplete resolution or unremitting and progressive. The history of arthritis progression was corroborated by reference to hospital records. Patients completed the Stanford health assessment questionnaire (HAQ) and hospital anxiety and depression scale (HADS) [17]. The severity of skin psoriasis was measured as a percentage of body surface area (BSA). In addition a global assessment of skin involvement was made using a scale of nil, mild, moderate, severe and very severe. All 103 patients were invited for a second visit, which included assessment of their skin and nail disease by a dermatologist (BG). We report results from the 69 patients who attended both visits. The mean and standard error of the mean (SEM) time interval between the first and second study visit was 7.0 (0.6) months. On the second visit, in addition to a full dermatological history and examination, the pattern of disease in all 20 nails was documented. A total of 1377 nails were examined in detail (three nails were not assessable due to previous trauma).
We analysed the severity of nail disease using an extension of the fingernail score described by Jones et al. [6] to also include toenails. All 20 nails were assessed for pitting, onycholysis, hyperkeratosis and severe nail deformity with involvement of both sides of the nail (dystrophy). Each of the listed features scored 1 with a possible maximum score of 80. This score is referred to as the psoriasis nail severity score (PNSS).
To determine the ability of the rheumatologists to detect psoriatic nail disease, the rheumatology and dermatology assessments were compared. The rheumatologists (LW or JD) assessed whether there was any evidence of psoriatic nail disease at the first visit. On the second visit the dermatologist (BG) assessed the severity of nail disease measured by the PNSS. The dermatologist was blinded to the rheumatology assessment.
The presence of HLA-B27 was tested by polymerase chain reaction using sequence-specific primers [18]. HLA-B27 results were available for 67/69 patients who underwent full nail assessment.
The association between PNSS and other clinical variables was explored initially using Student's t-tests and 2 tests. Because some of the clinical variables may interact, we used regression methods to adjust the relationship between two variables for the possible influence of a third variable. Linear regression was used to retest relationships between PNSS and the other clinical variables (%BSA skin affected by psoriasis, HAQ, presence of progressive and unremitting arthritis and depression scores), adjusting for the presence or absence of DIP joint disease by adding this dichotomous variable to each regression model. A further analysis of the joint relationship of PNSS with HAQ and %BSA affected by psoriasis was carried out, also using regression methods. The analysis was carried out using Excel and Stata [19]. Unless otherwise stated, values are represented as mean (SEM).
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Results |
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Patients had received a median of four (08) treatments for their skin disease. Only three (4%) patients had received no treatment for their skin disease. Most commonly prescribed were topical steroids, tar-based topical therapies and calcipotriol.
Although over 80% of patients had clinically evident nail disease, only one patient (1%) had received any treatment for nail disease. This patient had been treated with topical corticosteroids.
Severity of nail disease and skin disease
Severe nail disease as measured by the PNSS was strongly associated with severe skin disease (Fig. 1). The PNSS correlated with percentage body surface area (%BSA) affected by psoriasis (r = 0.34, P = 0.004) and physician global assessment of psoriasis (r = 0.45, P<0.001). In addition, other indicators of skin severity such as the number of psoriasis treatments (P = 0.002) and hospital admissions for psoriasis (P = 0.005) were associated with severe nail disease. However, there was no association with particular patterns of skin disease and the severity of nail disease.
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Using the PNSS, severity of nail disease was associated with polyarticular disease (P = 0.02) and unremitting and progressive arthritis (P<0.001) (Fig. 2).
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Regression analysis
Univariate analysis showed that there was an association between HAQ and extent of psoriasis as measured by %BSA affected (P = 0.04). When both were included in the same analysis, they were each still significantly associated with PNSS (Table 2a). We also analysed the data adjusting for the presence of DIP joint disease, and found that the associations between PNSS and indicators of skin disease, joint disease and functional status persisted (Table 2b).
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Of the 9 patients considered by the rheumatologists to have psoriatic nail disease, but with a PNSS of <10, the dermatology diagnoses were: nail trauma (2 patients), onychomycosis (2), onychoschizia (1), very mild psoriatic nail changes (3) and no significant nail disease (1).
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Discussion |
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This study has also confirmed that despite previous reports showing nail disease to be an important determinant of functional impairment in psoriasis [8], management of nail disease is often overlooked. Although most of our patients had received treatment for skin disease and had regular specialist rheumatology out-patient assessments, only one had received any treatment for nail disease. One possible explanation for this under-treatment is that therapies for psoriatic nail disease are perceived to be ineffective. However, nail disease has also been overlooked in published clinical trials in PsA. There have been case reports suggesting that DMARDs such as sulphasalazine and cyclosporin [21, 22] used for psoriasis or PsA have a therapeutic benefit in nail disease. Yet, despite increasing numbers of clinical trials for PsA, very few of these studies report the severity of nail disease at baseline, or the effect of treatment on the severity of nail disease.
Another explanation for the lack of attention to nail disease is that rheumatologists are poor at detecting nail disease. To examine this possibility, we compared the rheumatology and dermatology assessments of nail disease. Our study shows that a rheumatology assessment of nail disease is actually highly sensitive at detecting disease. Rheumatology assessment had a positive predictive value of 84% and negative predictive value of 83%. Although the rheumatology assessment lacked specificity, this is arguably less important when considering screening for nail disease in the rheumatology clinic. The good correlation between rheumatology and dermatology nail assessments, despite the time interval between the two study visits, lends weight to our conclusion that rheumatologists are able to make competent assessments of nail disease in PsA.
Why is the nail assessment important? It has been reported that in patients with psoriasis, nail disease causes cosmetic problems in 93%, pain in 52% and difficulty with activities of daily living in 58% [8]. Our study extends this knowledge to show that in PsA patients with severe nail disease also have greater functional impairment. In addition, severe nail disease correlates with greater anxiety and depression scores in patients with established PsA. While we have not shown that nail disease is the reason for such functional and emotional difficulty, these findings raise the possibility that severity of nail disease may be a prognostic indicator in patients presenting with PsA. Prospective studies of patients presenting with early disease are required to confirm this hypothesis.
Detection of nail disease is also important because treatments, although not perfect, are improving. The most practicable management involves the use of topical steroid and vitamin D analogues. Daily application for at least 3 months will result in a significant improvement in both nail signs and symptoms [10]. Basic nail care is important, and patients need to trim onycholytic nails so that the treatment can be applied to the nail bed. Triamcinolone injections into the nail fold are effective [11] but often require ring blocks and are less popular. Acitretin, a systemic vitamin A analogue used in skin psoriasis, may be specifically beneficial for the treatment of subungual hyperkeratosis [12]. A recent placebo-controlled trial of topical oil-dissolved cyclosporin A solution showed this treatment to be effective, safe and cosmetically acceptable [13]. Although not formally assessed in clinical trials, DMARDs such as methotrexate and cyclosporin A may also be of therapeutic benefit.
In summary, the severity of nail disease correlates with indicators of both skin and joint disease severity in PsA. This aspect of PsA is often overlooked in the clinic and in published therapeutic trials. Our study raises questions about the potential importance of nail disease in both understanding the underlying pathogenesis of PsA and also predicting outcome of early disease.
The authors have declared no conflicts of interest.
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Acknowledgments |
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References |
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