Prevalence of tension-type headache in adult general population: the PACE study and review of the literature.

The mean global prevalence of tension-type headache (TTH) in adult is 42 %. To date, there have been no Italian studies on TTH prevalence in the adult general population. Therefore, we conducted a cross-sectional study, called PACE (PArma CEfalea, or "Headache in Parma"), aimed at detecting the prevalence and clinical features of primary headaches in the city of Parma's adult general population. Crude past-year prevalence for definite TTH was 19.4 % (95 % CI 16.8-21.9), namely 9.0 % (95 % CI 7.1-10.8) for infrequent TTH, 9.8 % (95 % CI 7.9-11.8) for frequent TTH, and 0.6 % (95 % CI 0.1-1) for chronic TTH. Crude prevalence for probable TTH was 2.3 % (95 % CI 1.3-3.3). Our study results indicate a TTH prevalence rate (19.4 %) at the lower limit of data ranges currently available for Western countries, and prevalence rates for infrequent forms (9 %) do not appear much different from those of frequent forms (9.8 %).