Study | Year | Characteristics of the subjects | Instrument | FeNO value |
Travers et al. [23] | 2007 | New Zealand n = 193 (93 male and 100 female) Age 56.3±12.9 years 19 (9.8%) subjects were current smokers 46 (23.8%) subjects were atopic | NIOX system; Aerocrine AB, Solna, Sweden | Geometric mean 17.9 (90% CI 7.8–41.1) ppb, without adjustment for sex, atopy and smoking status |
Olivieri et al. [24] | 2006 | Italy n = 204 (102 male and 102 female) Age 36.1±9.9 years All nonsmokers Atopy not specified | CLD88; Ecomedics, Dürnten, Switzerland | Actual mean 11.7±5.0 ppb for males; 9.9±4.3 ppb for females |
Olin et al. [14] | 2007 | Sweden n = 1131 (558 male, 573 female) All never-smokers Age 50.3±13.81 years 286 (25.3%) had atopy | NIOX system | Geometric mean 16.6 (95% RI 5.87–47.14) ppb for the whole population Atopic subjects 18.8 (95% RI 6.03–58.74) ppb; nonatopic subjects 16.0 (95% RI 5.91–58.76) ppb Males 18.5 (95% RI 16.67–51.13) ppb; females 14.9 (95% RI 5.36–41.52) ppb |
Chng et al. [25] | 2005 | Singapore 45 normal subjects (34 with atopy and 11 with no atopy) Sex distribution not stated Mean (range) age 19.6 (18–27) years Smoking status unknown | NIOX system | Median (range) 38.4 (16.7–49.3) ppb for atopic subjects; 15.7 (11.5–21.7) ppb for nonatopic subjects |
Kim et al. [26] | 2010 | Korea n = 166 (80 male and 86 female) 80 (48.1%) subjects had atopy Age 33.2±12.1 years and 32.2±7.9 years for males and females, respectively (range 20–86 years) All non-smokers | NO analyser 280i; Sievers Instruments, Boulder, CO, USA | Mean FeNO of male and female subjects were 35.7±13.2 ppb and 26.0±14.2 ppb, respectively Mean FeNO of atopic males 37.3±12.1 ppb; nonatopic males 33.9±14.3 ppb; atopic females 28.6±17.7 ppb; and nonatopic females 24.1±10.6 ppb |
Tsang et al. [27] | 2001 | Hong Kong n = 120 (59 male and 61 female) All non-smokers Age of males 48.2±16.8 years; females 47.2±15.0 years Atopy not specified | Sievers NO analyser | Actual mean for males 34.5±25.7 ppb; females 23.1±14.7 ppb |
Current study | 2012 | Hong Kong n = 1093 (516 male and 577 female) All nonsmokers Age 47.3±16.6 years 645 (59.0%) subjects had atopy | NO analyser 280i | Geometric mean 32.6 (95% RI 31.4–33.7) ppb for all subjects Males 38.3 (95% RI 36.5–40.2) ppb; females 27.1 (25.8–28.5) ppb Atopic subjects 34.6 (95% RI 33.0–36.3) ppb; nonatopic subjects 29.8 (28.3–31.4) ppb |
Data are presented as mean±sd, unless otherwise stated. Only publications involving healthy adults with no known respiratory disease were selected. All instruments used a flow rate of flow rate of 50 mL·s−1.