Skin disorders in relation to oral contraception and other factors, including age, social class, smoking and body mass index. Findings in a large cohort study.

BACKGROUND: Over the years, a substantial number of scientific papers has been published considering the possible relationship between oral contraceptive use and various skin disorders.
OBJECTIVES: We aimed to investigate the possible effects of oral contraceptives and other factors including age, social class, smoking and body mass index on the occurrence of hospital referral for skin disorders within the Oxford Family Planning Association (Oxford-FPA) contraceptive study.
METHODS: We carried out a cohort study with long-term follow up of 17,032 women aged 25-39 years recruited at 17 family planning centres in England and Scotland between 1968 and 1974. The main outcome measure was the pattern of referral to hospital for skin disorders among the participants. The conditions considered (number of women affected in parentheses) were: malignant melanoma (48); other skin cancers (83); benign skin neoplasms (384); boils and cellulitis (334); eczema and dermatitis (327); erythematous disease (54); psoriasis (92); hypertrophic and atrophic conditions (59); diseases of the nails (80); diseases of the hair and hair follicles (74); diseases of the sebaceous glands (362); pigmented naevi (383); and unspecified eruptions (199). Some of these disease categories are broad, which complicates interpretation of the findings.
RESULTS: As the data relate to hospital referrals, while most skin disorders are largely managed within primary care, it is difficult to know to what extent our findings can be generalized to disease patterns in the community. None the less, a number of interesting results emerged. These included increased risks (approximately twofold) of referral to hospital for boils and cellulitis in heavy women, for psoriasis in women who smoke, and for pigmented naevi in women of higher social class. Referral for pigmented naevi was reduced by about half in women with a high body mass index. Of the oral contraceptive associations studied, we consider that only an increased risk of referral for eczema or dermatitis in current or recent pill users (relative risk 1.6, 95% confidence interval 1.2-2.1) might reflect a causal relationship. There was no increased risk in past users nor was the risk related to duration of use. These findings are very similar to those reported from the Royal College of General Practitioners oral contraception study.
CONCLUSIONS: Hospital referral for certain skin disorders was related to age, social class, smoking and body mass index within the Oxford-FPA study. Hospital referral for skin disorders generally seems to be unrelated to oral contraceptive use within the study, the possible exception being eczema and dermatitis, which occur more commonly in current and recent pill users than in non-users.