Psoriatic arthritis : is there a relationship of severity of nail disease to skin or joint disease?

الملخص EN

Objective : To examine the relationship between the severity of nail disease and severity of both skin and joint disease as well as functional assessment among psoriatic arthritis (PsA) patients.

Patients & Methods : Thirty two patients were included in the current study.

Pattern of arthritis was recorded and severity of joint disease was assessed using modified Ritchie index (adding DIPs, lumbar spine and sacroiliac joints) and scored as mild, moderate and severe.

Psoriatic skin patterns were recorded and severity of skin disease was assessed using the percentage of body surface area (% BSA) affected with psoriasis.

Severity of nail disease was assessed using Psoriasis Nail Severity Score (PNSS) where all the 20 nails were scored for pitting, onycholysis, hyperkeratosis and dystrophy.

Functional assessment was done using HAQ.

Finally, the presence of HLA-B17 and HLA-B27 were investigated.

Results : pattern of arthritis was as follows: polyarthritis was found in 19 patients (59.4 %), oligoarthritis in 7 (21.9 %), spondyloarthropathy in 4 (12.5 %), DIPs in 2 (6.2 %) and arthritis multilane was not found.

Modified Ritchie index was mild in 11 patients (34.4 %), moderate in 18(56.3 %) and severe in 3 (9.3 %).

As for skin disease pattern, psoriatic plaques were found in 25 patients (78.2 %), gut Tate in 4(12.5 %), combined gut Tate and plaques in 2(6.2 %) and postural psoriasis in 1(3.1 %).No erythrodermic or discoid pattern were found.

The percentage of involved BSA ranged from (2.8-44%).

Nail disease was detected in 26 patients (81.2%) and was distributed as follows: 6 patients (23 %) scored PNSS > 10, 13(50 %) scored 10-19, 5(19.4 %) scored 20-29 and 2(7.6 %) scored > 30.PNSS had no correlation with age or duration of arthritis but had significant positive correlation with skin disease duration (p < 0.01) and with % BSA (p < 0.01).

Also, PNSS had positive correlation with modified Ritchie index but not with HAQ which was found to correlate with modified Ritchie index (p < 0.05).

Low PNSS scores were found in positive HLA-B27 and not in positive HLA-B17 patients but overall, no significant correlation were found between them.

Conclusion : PNSS, as a simple and practical method, could be used as a good indicator for assessment of nail disease severity among psoriatic arthritis patients.

Also it correlates with duration and severity of skin involvement and severity of joint disease.

Research for disease pathogenesis at genetic and cellular level is still needed to understand the true link between psoriatic nail, skin and joint disease.