Scalp psoriasis and Dermatology Life Quality Index: A retrospective study based on 12-year data from the Malaysian Psoriasis Registry

INTRODUCTION: Psoriasis affects approximately 2–3% of the population worldwide, although the overall prevalence in Asia is <0.5%. Scalp psoriasis is a common initial presentation of psoriasis, which affects almost 80% of patients with psoriasis. METHOD: This retrospective descriptive study investigated 1,671 patients with psoriasis with scalp involvement registered with the Malaysian Psoriasis Registry (MPR) from January 2007 to December 2018. RESULTS: A total of 21,859 patients with psoriasis were registered with the MPR during the study period; among them, scalp involvement was seen in 7.6% (n= 1,671). Female sex preponderance (61%) was observed in the majority of Malay patients (58.5%), followed by the Chinese (16.9%), Indian (17.1%) and other ethnic patients (7.5%). A positive family history of psoriasis was identified in 22.7% (n=380). Approximately 34.8% (n=581) and 11% (n=172) of the patients had nail changes and psoriatic arthropathy, respectively. The mainstay treatment modality was topical treatment (93.6%), followed by systemic therapy (10%) and phototherapy (0.5%). The comorbidities found among the patients with scalp psoriasis included hypertension (27.9%), obesity (26%), dyslipidaemia (21%), diabetes mellitus (18.4%), ischaemic heart disease (5.4%) and cerebrovascular disease (1.3%). Approximately 23% reported a Dermatology Life Quality Index (DLQI) of >10, which indicated moderate-to-severe impairment. CONCLUSION: The proportion of patients with psoriasis with scalp involvement in our study (7.6%) is much lower than previous reports. Scalp psoriasis markedly negatively impacts the DLQI.