Surveillance and Surveys Higher Blood pressure among Inuit migrants in Denmark than among Inuit in Greenland Bjerregaard et al

Small group members Lisa Langsetmo Kateri Champagne Dana Teltsch Christel Renoux

Basic Information Study of prevalence Blood pressure Inuit in Greenland in Denmark 1216 participants in Greenland 680 participants in Denmark

Research Question “The purpose of this study was to compare the blood pressure between the Inuit of Greenland and the Inuit migrants in Denmark. Genetics (Inuit blood quantum), body mass index, education, smoking, alcohol, diet, and physical activity were analysed as possible determinants and confounders”

Sampling Greenland Two cities and four villages selected –Nuuk (random sample) –Quasigiannguit (all) –Uummannaq villages (all) Denmark Population register of people born in Greenland –Random sample of young and everyone over 45 mailed questionnaire –Random sample of respondants who were Inuit invited to participate

Critique Are study design and sampling methods appropriate to research question? –Study design is cross-sectional, outcome is prevalence. Appropriate. –Research question is comparison, sampling in two settings is different. Greenland sample is large, not clear it is representative. Denmark sample is random, but with response on first stage 77% and on second stage 55% possible selection bias.

Critique Is the sampling frame appropriate? –Sampling frame in Denmark is population register. Appropriate –Sampling frame in Greenland is selected towns, villages. No explanation is given. Was any attempt made at being representative? Was any attempt made at including towns and villages of different sizes, socio-economic status?

Critique Is the sample size adequate? –Overall sample size is good (1216 and 680) –Some strata were relatively small (e.g. over 65) –Some categories of confounders were merged in analysis (e.g cigarettes/day) –Characteristics of Denmark and Greenland sample were very different (e.g. 27% vs 45% male, 51% vs 89% full Inuit heritage)

Critique Are objective, suitable, and standard criteria used to measure outcome? –Blood pressure measured in hospital, resting, standard equipment, right arm, appropriate sized cuff, and averaged values –Unspecified detailed procedure, what is described in paper is not standard in Canada

Critique Is the outcome measured in an unbiased fashion? –Different times (8 a.m.-2 p.m. vs 8 a.m.-8 p.m.) –Different conditions (fasting and non-fasting) –Unspecified observer training, procedure details, inter and intra observer reliability, and blinding

Critique Is response rate adequate? –Greenland response rate was 66% Borderline –Denmark response rate was 54% Not good –Both were from non-random samples –Real rates smaller due to exclusions Are the refusers described? –Basic demographics known, reasons unknown –Demographics outside sample frame unknown

Critique Are the estimates of prevalence and incidence given with confidence intervals and in detail by subgroup? –Confidence intervals are given for whole groups and by subgroups where appropriate –Procedure used to calculate them unclear. –P-values also given. Unclear reason

Critique What are the implications of the results for action or intervention? –Found difference in mean blood pressure between residents of Greenland and Denmark not explained by other measured variables –Differences were consistent across categories of age and gender –Found strong correlation with educational background, which may be a proxy for “modernization”

Critique Other comments –Possible selection bias –Possible observation bias –Missing data –Populations were very different –Measurement of variables BMI, alcohol, physical activity

Comments Natural extensions of study –How does blood pressure of migrants differ from the general Danish population –How does the blood pressure of Greenlanders vary according to “modernization”