Table 1 Characteristics, prevalence and risk factors of acute mountain sickness among tourists above 15 years of age arriving in Lhasa, Tibet, China between June and October 2010

Gender

 Female

1072

387 (36.1)

1

1

 Male

1103

461 (41.8)

1.16 (1.04,1.29)

1.08 (0.94,1.23)

Age

  ≥ 55 years

360

116 (32.2)

1

1

  < 55 years

1796

722 (40.2)

1.25 (1.06,1.46)

1.29 (1.04,1.60)

Obesity

 No

2015

787 (39.1)

1

1

 Yes

119

48 (40.3)

1.03 (0.82,1.29)

1.02 (0.76,1.37)

Nationality

 Chinese

1018

401 (39.4)

1

1

 Other nationalities

1162

447 (38.5)

0.98 (0.88,1.09)

0.92 (0.78,1.08)

Altitude of permanent residence/home

 2000 m or higher (>6500 ft)

111

37 (33.3)

1

1

 Below 2000 m (<6500 ft)

1994

784 (39.3)

1.18 (0.90,1.54)

1.06 (0.76,1.49)

Education

 College or higher

1766

701 (39.7)

1

1

 High school or lower

361

130 (36.0)

1.10 (0.95,1.28)

1.11 (0.92,1.33)

Smoking

 No

1849

742 (40.1)

1

1

 Yes

251

83 (33.1)

0.76 (0.63,0.92)

0.75 (0.59,0.96)

Transportation

 Not by air

1138

409 (35.9)

1

1

 By air

1022

435 (42.6)

1.18 (1.07,1.32)

1.17 (1.02,1.34)

Health condition

 Good health

1904

710 (37.3)

1

1

 Poor or average health

197

117 (59.4)

1.59 (1.40,1.81)

1.63 (1.38,1.93)

Previous AMS symptoms

 No

1011

361 (35.7)

1

1

 Yes

590

221 (37.5)

1.05 (0.92,1.20)

1.10 (0.96,1.26)

Awareness of AMS

 No

248

92 (37.1)

1

1

 Yes

1851

732 (39.5)

0.94 (0.79,1.11)

1.02 (0.83,1.27)

Pre-exposure in the preceding 3 months

 No

1609

695 (43.2)

1

1

 Yes

552

148 (26.8)

0.62 (0.54,0.72)

0.71 (0.60,0.84)

Use of prophylactic

 No

1116

416 (37.3)

1

1

 Yes

965

399 (41.3)

1.11 (1.00,1.24)

1.05 (0.92,1.20)