Impact of a Newly Constructed Motor Vehicle Road on Altitude Illness in the Nepal Himalayas.

Objective: This study investigated the impact that motor vehicle travel along a newly constructed road has on altitude illness (including acute mountain sickness, high-altitude cerebral edema, and high-altitude pulmonary edema). The new road from Besisahar (760 m) to Manang (3540 m) in Nepal was completed in December 2014.

Methods: We enrolled all patients diagnosed with altitude illness at the Himalayan Rescue Association Manang clinic in fall 2016. Phi coefficients were calculated to test for an association between Nepali ethnicity and rapid ascent by motor vehicle. A retrospective review looked at all patients with altitude illness from fall (September-November) 2010 to spring (February-May) 2016.

Results: In fall 2016, more than half (54%) of patients with altitude illness traveled to Manang by motor vehicle, and one-third (33%) reached Manang from low altitude (Besisahar) in less than 48 hours. Nepali nationality had a significant association with motor vehicle travel (phi +0.69, P < .0001) as well as with rapid ascent to Manang (phi +0.72, P < .0001). Compared to previous seasons, fall 2016 saw the most patients diagnosed with altitude illness. The proportion of people with altitude illness who traveled by vehicle and reached Manang in less than 48 hours was significantly greater than the proportion prior to completion of the road (P < .0001 for both).

Conclusions: Rapid ascent by the newly constructed road from Besisahar to Manang appears to be related to a significant increase in the number of patients with all forms of altitude illness, especially among Nepalis. The authors believe that educational interventions emphasizing prevention are urgently needed.