Incidence of frostbite and ambient temperature in Finland, 1986-1995. A national study based on hospital admissions.

OBJECTIVES: The association of frostbite with ambient temperature in Finland is not known. The present study determined the incidence of frostbite and its association with sex, age and ambient temperature in a nationwide sample.

STUDY DESIGN: The first admissions of all patients (n=1,275) admitted to hospital in Finland during the period 1986-1995 with frostbite as a principal or secondary diagnosis were associated with ambient temperature on the day of admission.

RESULTS: The incidence of frostbite was 2.5 per 100,000 inhabitants, it was higher in males than females and increased linearly with age. The annual incidence of frostbite started to rise at below -15 degrees C and was considerable at under -20 degrees C, particularly in northern Finland. However, the daily incidence increased most in the urban area of Helsinki.

CONCLUSION: In the north, the main factor is the large number of cold days in the year. The daily incidence may be affected by urban lifestyle, possibly fashion, and inability to protect oneself against the cold.