Lung Function in Greenlandic and Danish Children and Adolescents

ARTICLE IN PRESS

Respiratory Medicine (2005) 99, 363–371

Lung function in Greenlandic and Danish children and adolescents

Tyra Grove Krausea,Ã, Bo V. Pedersena, Simon Francis Thomsenb, Anders Kocha, Jan Wohlfahrta, Vibeke Backerb, Mads Melbyea aDepartment of Epidemiology Research, Danish Epidemiology Science Centre, Statens Serum Institut, Artillertivej 5, DK 2300 Copenhagen S, Denmark bDepartment of Internal Medicine, Respiratory Unit, Bispebjerg Hospital, Bispebjerg Bakke 23, DK 2400 Copenhagen N, Denmark

Received 12 March 2003; accepted 19 July 2004

KEYWORDS Summary Respiratory morbidity in Inuit children is high. However, little is know Denmark; regarding lung function measures in this population. Greenland; The forced expiratory volumes in one second (FEV1) and forced vital capacity Inuit; (FVC) in 888 Greenlandic Inuits (N ¼ 888) and Danes (N ¼ 477) aged 6–18 years were Lung function; compared. Furthermore, associations between level of lung function and atopy and Spirometry; lifestyle factors were estimated in Greenlanders. Children The effect of height on FEV1 and FVC was signiﬁcantly different in Greenlanders and Danes, this difference in lung function increased with increasing height, and could not be explained by differences in age weight and BMI. Thus, Greenlanders taller than 130 cm had up to 300–400 ml higher FEV1 and FVC compared with Danes of the same height. Among Greenlanders, those living in settlements had the highest levels of both FEV1 and FVC. Greenlanders had elevated levels of FEV1 and FVC compared with Danes. The Inuit having a shorter limb length in relation to trunk height may account for these differences. However, our ﬁnding that Greenlanders living in settlements had the highest lung function level also suggests a possible role of factors in the traditional Greenlandic lifestyle. r 2004 Elsevier Ltd. All rights reserved.

Introduction

Respiratory morbidity is high among children in Inuit populations. In particular, lower airway infec- ÃCorresponding author. Tel.: +45-32-68-81-86, fax: +45-32-68- 31-65. tions are very common. Among Alaskan native E-mail address: [email protected] (T.G. Krause). children under one year of age bronchiolitis

364 T.G. Krause et al. hospitalisations are two to three times higher than in mately 10% of the population living in Greenland American Caucasian children.1,2 Also Canadian and have been born outside Greenland, primarily in Greenlandic Inuit children have been shown to have Denmark,16 as Greenland is a part of the Danish a very high rate of lower respiratory tract infections Kingdom. We undertook a cross-sectional study in compared with both developed and undeveloped November 1998 in the community of Sisimiut, countries,3,4 and respiratory tract infections account which is the second largest town in Greenland for 34% of all contacts to general practitioners (5500 inhabitants) located on the west coast of the among children aged 0–14 years in Greenland.5 island. All children and adolescents aged 6–18 years Pneumonia and bronchitis before two years of age and attending the schools in Sisimiut town and the has shown to be associated with deficits in forced neighbouring settlements Sarfannguaq and Itilleq expiratory volume in one second (FEV1) and forced were invited to participate in the study. Of 1213 vital capacity (FVC) in adulthood.6 Another risk eligible subjects 1054 (87%) had their lung function factor for both respiratory morbidity and reduced measured by spirometry. A total of 141 individuals, lung function levels is exposure to environmental mostly young children were subsequently excluded tobacco smoke.7–9 In Greenland approximately 80% due to failure to cooperate to spirometry. A further of the adult population smoke,10 and more than 50% nine subjects were excluded due to a transient of all children are during their first years of life failure with the Vitalographs and due to missing passively being exposed to smoking in their homes.4 measurements of height. Finally, 16 individuals (2%) Whereas a dramatic increase in atopy among were excluded as both parents were born outside Greenlanders has been reported recently,11 little is Greenland leaving 888 (73%) Inuit children and known about the prevalence of asthma in Inuit adolescents as the study population. Of these 888 populations. Early data going more than 20 years children 863 (97%) had a venous blood sample back will indicate a low incidence of hospitalisa- drawn, which was subsequently analysed for tions due to asthma.12,13 More recently a ques- specific IgE against the most common inhalant tionnaire study performed in an area in the allergens with the Phadiatops test which tests for southwest of Alaska where 82% of the inhabitants all allergens in one pool (grass, birch, mugwort, are Yup’ik Eskimos reported that 8% of children dog, cat, horse, Cladosporum Herbarum, house- aged 11–16 years had experienced periods of dust mite). Those who had a positive Phadiatops wheezing within the previous 12 months, and 10% test were considered atopic. Of the 888 Inuit had at least once been diagnosed with asthma by a children and adolescents 880 (99%) answered a physician.14 Only one study has attempted to more self-administered questionnaire together with their specifically assess the prevalence of asthma and parents regarding socio-demographic variables and atopy among Inuit (Canadian) school children and risk factors for respiratory disease. The question- those investigators found that both the prevalence naire was distributed in both a Danish and Green- of atopy measured by skin prick test and bronchial landic translation. Information on parents’ place of hyper-responsiveness measured by exercise test birth was obtained from the Danish Civil Registra- was low (5%).15 tion System (CRS) where all Danish and Greenlandic The present study was undertaken to provide a citizens are registered. better understanding of the underlying lung function in an Inuit population. We specifically intended to compare lung function levels in Greenlandic Inuit The Danish study population and Danish Caucasian children and adolescents, measured with the same equipment and the same In the year 2000 a study of asthma in Danish technique. Furthermore, we investigated whether children and adolescents was carried out in atopy and other potential risk factors were asso- Copenhagen.17 Danish children and adolescents ciated with level of lung function (FEV1 and FVC) in born in the first week of every month, living in an Inuit population. the surroundings of the University of Copenhagen, and aged 7–17 years at the time of the enrolment were drawn from the CRS and invited by mail to participate. Of 1440 Danish subjects who were Methods invited to participate by mail a total of 480 subjects (33.3%) agreed to participate in the The Greenlandic study population clinical examination study. Three subjects with missing measurements of height were subsequently Greenland is an Arctic Island with 52,000 inhabi- excluded, leaving 477 subjects for the study. A tants, of whom the majority are Inuits. Approxi- representative subset of the non-responders ARTICLE IN PRESS

Lung function in Greenlandic and Danish children 365

(N ¼ 116) were interviewed and found not to differ estimated in Inuit children. Effects were evaluated significantly from the participants with respect to in a model similar to the ones used for comparing respiratory symptoms and anthropometrical data. lung function in Danish and Inuit children. The Participants were asked not to smoke or take results presented were controlled for age, sex, medication for asthma before the examination, height, BMI and an interaction term between sex and if they had a recent viral infection, the and height. Significances of effects remained un- examination was postponed for at least 6 weeks. changed and estimated effects only slightly changed in various simpler models, than the one actually used. Spirometry All statistical analyses were carried out in SAS. In both studies spirometry was performed with a Vitalographs in standing position and without a nose-clamp, but otherwise according to the guide- Results lines of the European Respiratory Society.18 In the Danish study all spirometrys were performed by Table 1 presents the average age, weight, BMI, two medical students and in the Greenlandic study FEV , FVC, and the FEV /FVC-ratio according to by two nurses, all had been trained by two of the 1 1 height in Greenlandic and Danish children and authors, and in both studies one of the authors was adolescents. Greenlanders were generally older, also present during all examinations. The Vitalo- had higher BMIs and weights than Danes of the same graph was calibrated daily. Each measurement height. consisted of at least three maximal expiratory Fig. 1 presents the raw data and a polynomial manoeuvres from total lung capacity to residual curve of the estimated means of FEV and FVC in volume with a variation of less than 5% in FEV and 1 1 Greenlandic and Danish boys and girls according to FVC. The highest FEV and FVC were used in the 1 height. The level of FEV and FVC according to analyses. The subjects’ height was measured with- 1 height differed for Greenlandic and Danish boys out shoes. Weight was measured without shoes, but (P ¼ 0:004; P ¼ 0:0001) and girls with light indoor clothing. FEV1 FVC (PFEV1 ¼ 0:003; pFVC ¼ 0:0001). The overall ethnic difference was the same regardless of gender, but Statistical methods varied with height. Thus differences were primarily seen in the upper height group, while FEV1 and FVC The association between age, height, weight, BMI appeared similar for lower heights. As an example, and ethnicity (Greenlandic/Danish), and the level a Greenlander and a Dane of 130 cm would have of FEV1, FVC, and the FEV1/FVC-ratio was described approximately the same FEV1 and FVC whereas a in variance/regression models, separately for each Greenlander of 160 cm would have a 180 ml higher gender. Log-transformed spirometric measure- FEV1 and a 300 ml higher FVC compared with a Dane ments are often used in the literature to stabilise of the same height. The difference was smaller, but variances, however in our material residual plots still highly significant, after taking account of the indicated that log transformation would rather ethnic differences in age and BMI at a given height create a problem of variance heteroscedasity than (Pboys; FEV1 ¼ 0:003; Pboys;FVCo0:0001; Pgirls; FEV1 ¼ solving it. In all analyses best fits were obtained 0:007; Pgirls;FVC ¼ 0:0005). Thus, after adjustment when age, height, and body mass index (BMI) were for age and BMI the estimated difference in FEV1 treated as continuous variables. Because of the and FVC at 160 cm was 100 and 200 ml, respec- non-linearity of the effect of both age and height, tively. first- and second-order terms were included in the Table 2 presents the adjusted differences in FEV1 model. It was found that regression including and FVC in Greenlandic children and adolescents height (including second- and third-order terms) according to different medical conditions and gave a better description than a similar one lifestyle factors. Atopy was not associated with including age. Test for ethnic differences in the FEV1 and FVC, but Greenlanders living in settle- association between lung function level and height ments and Greenlanders who smoked themselves was evaluated by introducing an interaction term had higher levels of both FEV1 and FVC after between ethnicity and height. Our main finding of a adjustment for age, sex, height, BMI and a different effect of height in Danish and Inuit sex–height interaction. Exposure to passive smok- children remained significant in all models. ing at home was significantly associated with FVC, The association between medical conditions and however the direction of the effect differed in various lifestyle factors and lung function was only different smoking categories. When all significant ARTICLE IN PRESS

366 T.G. Krause et al. 4.9 4.4 4.3 9.0 6.0 6.3 7.1 4.9 5.5 5.4 4.5 5.5 6.1 7.3 7 7 7 7 7 7 7 7 7 7 7 7 7 7 — 91.0 — /FVC 1 8.76.9 91.4 7.0 90.3 6.3 91.2 5.5 89.3 5.3 91.4 89.8 8.1 5.05.8 87.9 5.3 88.4 5.4 87.0 7.4 89.3 5.2 86.8 86.2 6.9 90.4 7.8 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 SD 86.4 — 90.2 Mean FEV L 7 0.4 — 4.5 7 — 0.30.3 1.7 7 0.20.3 1.9 7 0.2 88.4 0.4 2.3 7 0.3 88.8 0.4 3.0 7 0.4 88.9 0.2 3.5 7 0.4 87.9 3.9 7 0.5 89.0 84.8 0.2 0.30.4 2.1 7 0.30.5 2.5 7 0.3 86.9 0.7 2.9 7 0.3 85.9 0.7 3.8 7 0.4 85.6 1.2 4.7 7 0.5 86.0 5.2 7 0.6 84.2 84.5 0.3 1.9 7 0.2 86.9 0.3 SD 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 1.3 — 1.5 Mean FVC L 7 0.20.2 1.6 0.3 2.0 0.4 2.5 0.4 3.3 0.4 3.7 4.4 0.0 0.30.3 2.2 0.2 2.6 0.4 3.3 0.4 4.2 0.4 4.9 5.2 0.2 1.8 — 4.1 7 — 1 0.2 3.5 7 0.2 1.0 4.5 7 0.2 1.7 7 0.2 SD — 1.1 7 1.3 7 L 7 Mean FEV 20.3 — — ) 2 /FVC-ratio according to height in Greenlandic (Gr) and Danish (DK) children and 1 — 16.7 17.0 Mean BMI (kg/m 66.0 — — , FVC, and FEV 1 — 22.7 22.9 Mean weight (kg) 17.5 — — — Mean age (years) N 0 2 433 255 455 222 Gr Dk Gr Dk Gr Dk Gr Dk Gr Dk Gr Dk Gr Dk children Number of children, mean age, weight, BMI, FEV – 129– 139– 149– 159 74– 169 73– 179 53 11 117 47 94 43 7.8 51 6 9.5 11.2 76 8.1 13.8 9.3 10.3 25 26.9 12.6 14.9 32.8 39.7 15.0 52.3 15.3 26.5 29.9 62.2 15.4 37.8 48.8 17.3 78.0 18.0 58.0 19.1 16.1 21.7 16.6 60.8 18.2 1.4 7 0.3 20.3 23.3 1.8 7 0.3 2.2 7 0.3 1.6 7 2.9 7 0.4 21.4 26.6 1.8 7 2.1 7 2.7 7 3.3 7 0.3 20.3 3.2 7 3.7 7 – 139– 149– 159 105– 169– 179 81 57 57 64 45 60 9.4 45 11.2 32 9.0 12.7 27 10.5 14.7 32.3 11.8 38.9 15.4 14.2 47.5 30.2 15.9 59.0 38.2 65.9 45.4 17.9 53.1 18.8 16.9 63.1 20.0 18.4 21.7 1.9 7 0.3 19.0 2.3 7 0.3 22.0 19.5 1.9 7 2.8 7 0.4 2.2 7 20.8 3.6 7 0.6 2.6 7 4.1 7 0.6 3.4 7 4.1 7 – 129 56 7 8.0 8.2 27.1 25.3 17.3 15.8 1.5 7 180 120 16 0 7.0 180 13 9 16.0 15.9 72.8 69.1 21.8 20.2 4.4 7 120 19 0 6.9 120 130 140 150 160 170 X o 130 140 150 160 170 X 120 o Height (cm) Number of Girls Boys Table 1 adolescents. ARTICLE IN PRESS

Lung function in Greenlandic and Danish children 367

Figure 1 The observed values and estimated means of FEV1 and FVC according to height in Greenlandic and Danish boys and girls. The means according to height were estimated on the basis of a third degree polynomial specific for each combination of ethnicity and sex. risk factors were included in a multivariate analy- Discussion sis the above-mentioned associations remained significant. Spirometry is an important tool in monitoring The FEV1/FVC-ratio was lower in Greenlanders respiratory health. However, lung function levels than in Danes (Pboys=0.0003, Pgirlso0.0001). This have not previously been determined in Green- difference remained significant after adjustment landic Inuits. In the present study we found Inuits to for BMI, which was the only factor associated with generally have higher lung function levels than the FEV1/FVC-ratio (Pboys=0.003, Pgirlso0.0001). Danes, but the effect of height on FEV1 and FVC was There was no interaction with height, BMI and significantly different in the two populations. Thus, ethnicity (data not shown). Of the risk factors Greenlandic Inuits shorter than 130 cm had the investigated only medication for asthma during the same or lower FEV1 compared with Danes, whereas last year had a significant, though moderate effect Inuits taller than 130 cm had up to 300–400 ml on the FEV1/FVC-ratio (P ¼ 0:03) (data not shown). higher FEV1 and FVC than Danes. These differences Thus, asthma medication reduced the FEV1/FVC- could not solely be explained by differences in age, ratio with 2.2% (from 88.4% to 86.2%). weight or BMI between Greenlanders and Danes of ARTICLE IN PRESS

368 T.G. Krause et al.

Table 2 Adjusted differences in level of FEV1 and FVC in Greenlandic children according to medical conditions and lifestyle factors.

No. Adjusted* P-valuey Adjusted* P-valuey differences differences in FEV1 (SD)ml in FVC (SD)ml

Doctor’s diagnosis of asthma ever Yes 57 75 (48) 0.12 81 (54) 0.13 No 761 ref. ref. Medication for asthma last year Yes 43 82 (54) 0.13 49 (61) 0.42 No 775 ref. ref. Atopy Yes 130 58 (33) 0.08 44 (37) 0.23 No 733 ref. ref. Parental place of birth Greenland/missing 79 37 (41) 0.56 54 (46) 0.15 Greenland/abroad 80 21 (41) 66 (46) Greenland/Greenland 721 ref. ref. Travel history Ever been outside Greenland 410 9 (24) 0.72 9 (28) 0.76 Never been outside Greenland 413 ref. ref. Place of living Settlement 27 154 (67) 0.02 170 (75) 0.02 Sisimiut town 853 ref. ref. Daycare attendance Yes 690 ref. (32) 0.39 ref. (37) 0.98 No 139 28 1 Number of persons in household 2 46 4 (57) 0.52 29 (63) 0.79 3 104 51 (44) 27 (48) 4 190 59 (36) 35 (40) 5 211 36 (36) 0 (39) X6 187 ref. ref. Indoor humidity Yes 134 39 (33) 0.23 38 (37) 0.31 No 653 ref. ref. Carpets in bedroom Wall-to-wall carpets 102 16 (38) 0.19 30 (42) 0.24 Loose carpets 164 56 (31) 48 (34) No carpets 583 ref. ref. Number of cigarettes smoked in household a day None 201 ref. 0.20 ref. 0.04 1–10 309 62 (29) 80 (33) 10–20 70 26 (45) 4 (51) 420 18 11 (77) 58 (87) Child’s own smoking Yes 100 104 (43) 0.02 203 (48) 0.001 No 711 ref. ref. Sledgedogs ever Yes 381 16 (25) 0.50 4 (27) 0.89 No 461 ref. ref. Cat ever Yes 87 20 (40) 0.61 7 (44) 0.88 No 756 ref. ref. ARTICLE IN PRESS

Lung function in Greenlandic and Danish children 369

Table 2 (continued )

No. Adjusted* P-valuey Adjusted* P-valuey differences differences in FEV1 (SD)ml in FVC (SD)ml

Dog ever (not sledgedogs) Yes 52 29 (50) 0.56 109 (56) 0.84 No 790 ref. ref. Mother’s educational status 8th grade/unskilled worker 216 ref. 0.35 ref. 0.56 9th–12th grade 205 17 (33) 46 (37) Skilled worker 230 39 (31) 44 (36) Baccelaureate/higher education 91 69 (42) 35 (47)

*Adjusted for age, sex, height, BMI and sex*height. yP-value testing heterogeneity.

the same height. These results may have clinical however, still within normal range and might be implications as Greenlandic children with subnor- explained by a rather high FVC in Greenlanders. mal lung volumes could falsely be classified as Greenlandic children are generally shorter and healthy if Danish children and adolescents be used have a broader body build compared with Danes, as reference population. which is also reflected in the higher weight and BMI Rode and Shephard previously reported that in Greenlanders according to height observed in our Canadian Inuits aged 11–19 years had higher FEV1 study. Sitting height was not measured in the and FVC, but a reduced FEV1/FVC ratio compared present study, but Inuits are known to have a larger to Caucasian standards, and that the differences sitting height ratio (sitting height/height) com- increased with age.19 Furthermore, they only found pared with Danes, and the difference increases a small difference in lung function levels between with age.21 A larger trunk at any given height could Canadian Inuit boys and girls. When we compared be one of the explanations for the increased lung FEV1 and FVC in Greenlandic children with similar function found in the Greenlandic subjects. measurements performed in Canadian Inuits of the We cannot exclude that differences in level of same age in 1989/1990,20 Greenlandic boys tended lung function between the two populations could to have higher FEV1 and FVC according to age also be due to differences in prevalence of compared with Canadian boys, whereas Green- respiratory diseases. However, as previously de- landic and Canadian girls had approximately similar scribed Inuit children have a very high rate of levels of FEV1 and FVC. We also found the sex respiratory tract infections compared with children difference of lung function in Greenlanders and from industrialised countries which would only tend Danes to be of a similar magnitude. to underestimate the observed difference in lung In the present study all Greenlandic school- function level. Furthermore only minor differences children were offered to participate in the study in lung function level was observed among children without any restrictions. In the Danish study diagnosed with asthma and receiving medication participants were asked not to smoke before the for asthma and others, indicating that differences examination, and if they had a recent respiratory in asthma prevalence between the two populations tract infection the examination was postponed for are unlikely to confound our results. at least 6 weeks. The different inclusion criteria Surprisingly, Greenlanders who smoked tended to may, if anything, have resulted in an underestima- have higher levels of both FEV1 and FVC. We do not tion of the observed differences in lung function believe this finding is due to a biological effect of between Greenlanders and Danes. Thus, in spite of smoking, as it is well described that smoking is a high rate of lower respiratory tract infections associated with an increased rate of lung function among young children in Greenland, and a high loss over time.22,23 It is rather a ‘‘healthy smoker proportion of children being exposed to environ- effect’’, which arises when individuals continue the mental tobacco smoke,4 Greenlandic children have smoking habit because his/her lungs are relatively higher levels of both FEV1 and FVC compared with resistant to the effects of smoking. The ‘‘healthy Danes. In contrast, the FEV1/FVC-ratio was lower in smoker effect’’ has been described previously and Greenlanders compared with Danes, but was, may particularly bias cross-sectional studies with ARTICLE IN PRESS

370 T.G. Krause et al. young adults, where smoking has not yet led to a ence is not likely to have any clinical relevance reduced lung function.24 We also found that passive (88.4% vs. 86.2%), and it therefore seems that exposure to smoking in the household was asso- Greenlandic children with asthma are sufficiently ciated with FVC, but the direction of the effect medicated in Greenland. differed in different smoking categories, and a We confined the Greenlandic study to subjects dose–response relationship would have been ex- with at least one parent who had been born in pected, had there been a causal relation between Greenland, as we used parental place of birth as a household smoking and FVC. Furthermore, a re- marker of ethnicity. Interestingly, there were no versed dose–response effect was observed between differences in lung function levels between Green- household smoking and FEV1, although the associa- landers with one compared to two parents born in tion was not significant. In a recently published Greenland. This might suggest that the stature and review based on pooled analyses of 21 surveys of lung function be highly influenced by genetic school children, parental smoking was associated factors such as having an Inuit parent. with small, but statistically significant deficits in In conclusion, Greenlanders taller than 130 cm 25 FEV1 and other spirometric indices. However, have elevated levels of both FEV1 and FVC based on the present results we cannot infer that compared with Danes. The Inuits having a shorter exposure to tobacco smoke in the household is limb length in relation to trunk height may account associated with a reduced lung function in Green- for these differences. However, our finding that landic children and adolescents. Greenlanders living in settlements had higher lung Greenlanders who lived in settlements had on function than those living in the town of Sisimiut average a 150 ml higher FEV1 and a 170 ml higher could indicate that also other factors contribute to FVC compared with those living in Sisimiut town. the level of lung function in Inuits. This is surprising as the housing and living conditions in general is of a lower standard in the settlements compared with Sisimiut town. Also, the frequency of contacts to the health care system is lower in the settlements. The increased lung References function may either be attributed to a selection 1. Lowther SA, Shay DK, Holman RC, Clarke MJ, Kaufman SF, phenomenon, i.e. that strong health is required in Anderson LJ. Bronchiolitis-associated hospitalizations among order to live under the rough conditions in the American Indian and Alaska Native children. Pediatr Infect settlement, or they could be attributed to factors Dis J 2000;19(1):11–7. in the more traditional Greenlandic lifestyle in the 2. Liu LL, Stout JW, Sullivan M, Solet D, Shay DK, Grossman DC. settlements. Of interest, those living in settle- Asthma and bronchiolitis hospitalizations among American Indian children. Arch Pediatr Adolesc Med 2000;154(10): ments have a higher intake of traditional Green- 991–6. landic food such as fish and sea mammals, which 3. Banerji A, Bell A, Mills EL, McDonald J, Subbarao K, Stark G, 26 contain high levels of o-3 fatty acids. A high et al. Lower respiratory tract infections in Inuit infants on dietary intake of fish has previously been found to Baffin Island. CMAJ 2001;164(13):1847–50. be associated with higher FEV in adults.27 Another 4. Koch A, Sorensen P, Molbak K, Pedersen FK, Mortensen T, 1 et al. Population-based study of acute respiratory in- explanation could be that children living in settle- fections in children, Greenland. Emerg Infect Dis 2002; ments are more physical active compared with 8(6):586–93. those living in Sisimiut town, in fact, physical 5. Niclasen BV. Disease pattern in children living in the Arctic: activity has been associated with higher lung visits to a general practitioner. Int J Circumpolar Health function levels,28 and adult Greenlanders living in 1998;57(Suppl 1):141–7. 6. Shaheen SO, Sterne JA, Tucker JS, Florey CD. Birth weight, settlements are more physical active than those 26 childhood lower respiratory tract infection, and adult lung living in towns. function. Thorax 1998;53(7):549–53. Lung function level was not associated with atopy 7. Bakoula CG, Kafritsa YJ, Kavadias GD, Lazopoulou DD, in Greenlanders, a finding similar to that observed Theodoridou MC, Maravelias KP, et al. Objective passive- by Hemmelgarn and Ernst among Canadian Inuits.15 smoking indicators and respiratory morbidity in young children. Lancet 1995;346(8970):280–1. This is in contrast to findings in other populations 8. Gilliland FD, Li YF, Peters JM. Effects of maternal smoking where allergic sensitisation to both indoor and during pregnancy and environmental tobacco smoke on outdoor allergens have been associated with asthma and wheezing in children. Am J Respir Crit Care Med 29,30 2001;163(2):429 36. reduced FEV1. Nor did FEV1 and FVC differ – according to diagnosis or medication for asthma, 9. Li YF, Gilliland FD, Berhane K, McConnell R, Gauderman WJ, Rappaport EB, et al. Effects of in utero and environmental but those who had received medication for asthma tobacco smoke exposure on lung function in boys and girls within the last year had reduced FEV1/FVC ratios with and without asthma. Am J Respir Crit Care Med compared to others. However, the observed differ- 2000;162(6):2097–104. ARTICLE IN PRESS

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10. Bjerregaard P, Mulvad G, Pedersen HS. Cardiovascular risk 22. Sandvik L, Erikssen G, Thaulow E. Long term effects of factors in Inuit of Greenland. Int J Epidemiol 1997;26: smoking on physical fitness and lung function: a longitudinal 1182–90. study of 1393 middle aged Norwegian men for seven years. 11. Krause T, Koch A, Friborg J, Poulsen LK, Kristensen B, Melbye BMJ 1995;311(7007):715–8. M. Frequency of atopy in the Arctic in 1987 and 1998. Lancet 23. Apostol GG, Jacobs Jr. DR, Tsai AW, Crow RS, Williams OD, 2002;360(9334):691–2. Townsend MC, et al. Early life factors contribute to the 12. Kromann N, Green A. Epidemiological studies in the decrease in lung function between ages 18 and 40: the Upernavik district, Greenland. Incidence of some chronic coronary artery risk development in young adults study. Am diseases 1950–1974. Acta Med Scand 1980;208:401–6. J Respir Crit Care Med 2002;166(2):166–72. 13. Herxheimer H, Schaefer O. Letter: asthma in Canadian 24. Becklake MR, Lalloo U. The ‘healthy smoker’: a phenomenon Eskimos. N Engl J Med 1974;291:1419. of health selection? Respiration 1990;57(3):137–44. 14. Stout JW, White LC, Redding GJ, Morray BH, Martinez PE, 25. Cook DG, Strachan DP, Carey IM. Health effects of passive Gergen PJ. Differences in asthma prevalence between smoking. 9. Parental smoking and spirometric indices in samples of American Indian and Alaska Native children. children. Thorax 1998;53(10):884–93. Public Health Rep 2001;116(1):51–7. 26. Bjerregaard P, Curtis T, Senderovitz F, Christensen U, Pars T. 15. Hemmelgarn B, Ernst P. Airway function among Inuit primary Diet and exercise. In: Living conditions, lifestyle, and health school children in far northern Quebec. Am J Respir Crit in Greenland. First ed. Copenhagen: DIKE; 1995. p. 61–74. Care Med 1997;156(6):1870–5. 27. Schwartz J, Weiss ST. The relationship of dietary fish intake 16. Greenland 2000 Statistical Yearbook. Statistics Greenland, to level of pulmonary function in the first National Health Greenland Home Rule; 2000. and Nutrition Survey (NHANES I). Eur Respir J 1994;7: 17. Thomsen SF, Ulrik CS, Larsen K, Backer V. Change in 1821–4. prevalence of asthma in Danish children and adolescents. 28. Holmen TL, Barrett-Connor E, Clausen J, Holmen J, Bjermer Ann Allergy Asthma Immunol 2004;92(5):506–11. L. Physical exercise, sports, and lung function in smoking 18. Standardized lung function testing. Official statement of the versus nonsmoking adolescents. Eur Respir J European Respiratory Society. Eur Respir J Suppl 1993;16: 2002;19(1):8–15. 1–100. 29. Sunyer J, Soriano J, Anto JM, Burgos F, Pereira A, Payo F, et 19. Rode A, Shephard RJ. Pulmonary function of Canadian al. Sensitization to individual allergens as risk factors Eskimos. Scand J Respir Dis 1973;54(4):191–205. for lower FEV1 in young adults. European Community 20. Rode A, Shephard RJ. Acculturation and the growth of lung Respiratory Health Survey. Int J Epidemiol 2000;29(1): function: three cross-sectional surveys of an Inuit commu- 125–30. nity. Respiration 1994;61(4):187–94. 30. Sears MR, Burrows B, Herbison GP, Flannery EM, Holdaway 21. Becker-Christensen FG. Growth in Greenland. Development MD. Atopy in childhood. III. Relationship with pulmonary of body proportions and menarcheal age. Ugeskr Laeger function and airway responsiveness. Clin Exp Allergy 2002;164(7):906–10. 1993;23(11):957–63.