Nail Involvement as a Predictor of Concomitant Psoriatic Arthritis in Patients With Psoriasis

A. Langenbruch; M.A. Radtke; M. Krensel; A. Jacobi; K. Reich; M. Augustin


The British Journal of Dermatology. 2014;171(5):1123-1128. 

In This Article

Abstract and Introduction


Background Patients with psoriatic arthritis (PsA) suffer from increased burden of disease and impairments in quality of life. Early detection and treatment of PsA could contribute to the prevention of clinical and radiological progression.

Objectives To analyse the predictive value of clinical and patient-reported outcomes for concomitant PsA in a population-based cohort of patients with psoriasis.

Methods We performed a retrospective analysis of data from three independent national cross-sectional studies on health care in psoriasis and PsA, conducted in Germany in the years 2005, 2007 and 2008. Patients with psoriasis were included in the study by dermatologists (n = 3520) and via the German patient advocacy group for psoriasis (n = 2449). In all studies, psoriasis history, clinical findings, PsA, nail involvement, health care and patient-reported outcomes were collected with standardized questionnaires.

Results In the regression model on 4146 patients the strongest predictors for concomitant PsA were nail involvement [odds ratio (OR) 2·93, 95% confidence interval (CI) 2·51–3·42, P < 0·001] and inpatient hospital treatment (OR 1·63, 95% CI 1·38–1·93, P < 0·001). By contrast, scalp involvement was not a significant predictor.

Conclusions Patients with psoriasis seen by dermatologists and those in patient advocacy groups show clinical indicators of PsA, the most predictive being nail disease. In practice, a comprehensive assessment of clinical findings associated with PsA is needed.


Psoriatic arthritis (PsA) is a psoriasis-related chronic, systemic inflammatory condition with typical signs and symptoms both of psoriasis and arthritis.[1] Results of two independent studies from Germany have shown an almost similar prevalence of 20·6% and 19·0%, respectively, in patients with psoriasis referring to dermatologists.[2,3]

Patients with PsA have reduced quality of life and functional capacity compared with patients with psoriasis in general and – even more – compared with healthy controls.[4,5] In half of the patients, aggravation of joint damage, which may lead to deformities, has been noted within the first 2 years of disease.[6] Because joint disease can lead to irreversible bone damage, there is an indication for early detection and treatment of any arthritic affliction in psoriasis. For this, an increasing number of dermatologists are dedicated to identifying signs and symptoms suspicious for PsA. Conversely, rheumatologists, who may see markedly different subgroups of patients with PsA, should focus on skin lesions associated with PsA. For both groups of physicians, indicators and predictors of PsA permitting early detection of disease are of considerable clinical interest. If validated properly, they may help to identify patients at risk of deterioration.

Especially, nail involvement, scalp afflictions and intergluteal/perianal psoriatic lesions are associated with a higher likelihood of developing PsA and are therefore regarded as major predictors of PsA.[7,8] For instance, nail lesions were found in about 40–45% of patients with psoriasis only and in about 87% of patients with PsA.[9,10]

The nail is just as much a part of the anatomical functional unit of the enthesis as of the skin.[11] The fascia of the enthesis transitions into and is continuous with the nail root.[12] McGonagle[12] and Tan et al.[13] used magnetic resonance imaging (MRI) of the finger to study the anatomical correlations. Histologically, and with high-resolution MRI, one could see that the extensor tendon that crosses the distal interphalangeal (DIP) joint is connected with the nail root and matrix via tendinous fibres surrounding the root.[13] In PsA there is nearly always enthesitis of the DIP joint in the early phase of disease. The inflammatory reaction may be severe, even affecting the nail matrix. This close relationship between the nail, tendinous attachment to the bone, and periosteum may explain why patients with psoriatic arthritis, who typically have inflammatory changes affecting the DIP joint, often develop inflammation of the nail, too.

Psoriatic arthritis is often prone to be overlooked.[3] Because more than 80% of patients with PsA present symptoms of psoriasis before developing symptoms of PsA,[14] dermatologists are in a unique position to detect PsA earlier in the disease process through regular, routine screening of patients with psoriasis. Therefore, active monitoring of patients with psoriasis for signs of joint or arthritic involvement and familiarity with PsA screening, diagnosis and treatment options can help dermatologists to positively impact the clinical course of psoriatic disease. Distinguishing clinical features of PsA include nail involvement in the vast majority of cases. The severity of nail involvement is determined by the site of the inflammatory reaction. If the nail matrix is involved, there may be development of indentations (pitting), leukonychia, red patches in the lunula, and onychodystrophy. Severe nail psoriasis can result in the crumbling of the nail. If the nail bed is affected, typical 'oil spots', splinter haemorrhage, onycholysis, and subungual parakeratosis and hyperkeratosis can be observed.

The main objective of the present analysis was the identification of significant clinical and patient-reported predictors for concomitant psoriatic arthritis in a population-based cohort of patients with psoriasis. For this purpose we performed an analysis of data, derived from three independent national cross-sectional studies on health care in psoriasis and psoriatic arthritis, conducted in Germany in the years 2005, 2007 and 2008.

The research questions raised were the following:

  1. How do patients with PsA, who are treated in dermatology settings, differ from patients without PsA?

  2. What are the strongest predictors of PsA?