Nickel allergy and hand dermatitis in a stratified sample of the Danish female population: an epidemiological study including a statistic appendix.

The occurrence of nickel allergy and hand eczema has been investigated in a stratified sample (2 500) of the Danish female population by an interview technique. The incidence density (allergy intensity) has been estimated by standard maximum likelihood methods. The age-specific prevalence rates have been calculated by life table techniques. The incidence density has doubled in all age groups from 1948 to 1973. The highest prevalence rate of nickel allergy was found in the 45-year-olds (0.189 +/- 0.023). The possible interaction between nickel allergy and hand eczema was analysed by a Markov chain model. Compared with non-nickel-sensitive women, a woman who has become nickel sensitized ran an increased risk of developing hand eczema. And those who had first developed hand eczema ran an increased risk of subsequently developing nickel allergy. In future efforts to reduce direct skin contact with nickel, the close relation between nickel allergy and hand eczema should be the main argument. Statistical methods based on the incidence density will be useful in the evaluation of these efforts.