Background: Altitude diseases, the most frequent of which is acute mountain sickness (AMS), are among the most common and serious problems that recreational and professional mountain athletes may encounter. If left undiagnosed, they may lead to lethal consequences. In a cross sectional study, we investigate the prevalence of AMS disorder among the overnight guests of a mountain resort hotel.

Methods: Overnight guests staying at Hotel Tochal (elevation 3545 m), near Tehran, Iran, in the winter of 2006 constituted the study participants. A questionnaire, including demographic data, proposed risk factors and Lake Louise score, was completed by a physician for all who had headache or other symptoms of AMS. Data from daily hotel reception records were also collected.

Results: Overall, 328 persons stayed at this hotel for at least one night during the study period. Among these, 47 persons (14.3%) were admitted to the clinic for headache. According to the physician's diagnoses, only 34 guests (10.4%; 95% CI: 7.1-13.7%) were affected by AMS. The concurrent symptoms of headache and vertigo or insomnia had the highest predictive value for AMS diagnosis. Ambiguous headache had a higher predictive value than other types of headache.

Conclusions: Despite the height of Tochal peak and the frequent use of high speed telecabin, it seems that the frequency of AMS is lower than that found in other studies on similar altitudes. However, more research should be done in this regard.