Incidence of polyneuropathy in Utrecht, the Netherlands.

Objective: Ascertain the incidence of cryptogenic axonal polyneuropathy (CAP) and how this relates to the overall incidence of polyneuropathy.

Methods: Electronic diagnostic registries of all hospital-based neurologic practices in the province of Utrecht (population 1,224,852 = 7.4% of the Dutch population) were consulted in 2010 to identify incident cases with polyneuropathy. Medical files were reviewed to specify the final diagnosis. Age-adjusted incidence rates for the Netherlands were calculated using national age-specific population figures.

Results: The overall incidence of polyneuropathy was 77.0/100,000 person-years (95% confidence interval 71.1-82.8) in persons aged 18 years and older. Diabetic polyneuropathy (32%), CAP (26%), toxic polyneuropathy (14%), and immune-mediated polyneuropathy (9%) were the most frequent diagnoses. The incidence of CAP was 31.6/100,000 person-years (95% confidence interval 27.0-36.3) in persons aged 40 years and older. The incidence of polyneuropathy increased with age, as well as the proportion of patients diagnosed with CAP: 12% (40-49 years), 20% (50-59 years), 28% (60-69 years), 32% (70-79 years), and 35% (≥80 years) (χ(2) test, p = 0.005).

Conclusions: The chance of establishing an etiologic diagnosis in patients presenting with a polyneuropathy decreases with age. Given the aging population, polyneuropathy in general and CAP in particular will pose a growing health care problem.