Measurements in circumpolar populations: applying a questioning mind

KEYWORDS:

•  Measurement
• circumpolar
• inuit
• first nations
• indigenous
• health

In a recent issue of the IJCH, Laustsen et al. published the results of a study of lung function in Greenlandic seafood workers who are primarily of Inuit ancestry [1]. The impetus for their study was the recognition that spirometry measurements including forced expiratory volume in the initial second of expiration (FEV1), and forced vital capacity (FVC), differ according to ancestry due to factors including the relationship between standing height and thoracic size. Recognition that the sitting height to standing height ratio (Cormic index) varies between people of different ancestral backgrounds has led to the use of separate reference equations for people of African American background [2].

Unsurprisingly, Laustsen and colleagues found that when Global Lung Initiative reference equations, which are derived from people of European ancestry, are used in the calculation of the lung function of Inuit seafood workers, the resultant values suggest above normal lung function. Modification of the recorded height of the seafood workers to incorporate established differences in their Cormic index yielded more credible results.

The study is clearly of interest and relevance to circumpolar clinicians who see patients with respiratory conditions. The paper, however, has another message to those who provide all forms of care in these regions. Many circumpolar health care workers are trained in southern educational institutions using curricula that are focused on southern populations [3]. Circumpolar countries have focused increasingly on the need for cultural education of health workers as part of the hiring process for those wishing to work among northern Indigenous peoples [4]. This is a very important part of a process of decolonisation and reconciliation. There is also a need to ensure that health workers, circumpolar or otherwise, bring to their work a basic and applied scientific knowledge base that is specific to the people for whom they care [3].

In circumpolar settings, the questioning mind engages in a process to “decolonise” our assessments by asking whether the various measures that we use are entirely applicable or accurate. Are they based on different reference populations, and are there ways to test their validity in other groups? Whether in the context of circumpolar or any other group of people, exercising caution in applying reference values that have been generated in larger populations is not a new concept or practice. Laustsen and colleagues remind us that the questioning mind is a prerequisite for all good research. Reading the paper leads us to the clinic room, reminding us of the need for clinicians, health systems and training programs to incorporate the results, and the mind frame, in our practice.

In some cases the clinical measurements that have been applied in circumpolar populations have led to inaccurate conclusions. A 1995 study of Inuit children in Igloolik demonstrated that growth charts based on non-Inuit populations did not accurately reflect the health and nutritional status of the children, and led to erroneous labelling of the Inuit as obese [5]. Among Canadian and Greenlandic Inuit, the application of World Health Organization definitions of obesity based on body mass index (BMI) measurements may overestimate the prevalence of obesity among the Inuit [6,7]. Measurement studies in Inuit populations may lack nuance, or sometimes the measurement is not so much the problem as the interpretation. In a 2012 review of obesity studies in the circumpolar Inuit, Galloway and colleagues pointed out the need to discriminate between visceral abdominal fat and subcutaneous fat, and observed that for given levels of central obesity, Inuit have lower levels of blood pressure, glucose, insulin and triglycerides compared to non-Inuit [8].

Other examples are apparent. Andersen et al. found that creatinine excretion was lower among Inuit than among Caucasians in Greenland, controlling for age, gender, weight and BMI [9]. The authors point out that the use of the urinary creatinine excretion for Caucasians when calculating the albumin/creatinine ratio in Inuit patients will lead to underestimation of albumin excretion, and offer a regression equation in order to correct for this.

Reference values established in non-Indigenous populations should be scrutinised when applied to other groups. In a study of haemoglobin concentrations among Greenlanders and Danes, Milman et al. found that the former had significantly lower values than the latter, raising the possibility of genetic differences between the two populations and questioning established reference definitions [10]. Anemia unexplained by iron deficiency has also been demonstrated among Inuit men and women over 50 years of age in northern Canada; the authors suggest non-genetic factors including inflammation and infection as possible causal factors [11].

In the case of vitamin D, observations among circumpolar peoples inform the global community’s debate regarding what measurements best reflect health, and what values we can call “normal” [12]. Studies among Greenlandic and Canadian Inuit as well as northern First Nations peoples demonstrate genetic adaption to vitamin D scarcity, including increased conversion of 25-hydroxyvitamin D to 1,25dihydroxyvitamin D, higher serum levels and activity of vitamin D binding protein, and increased activity of specific vitamin D receptor genotypes [12–15].

As caregivers and researchers, we bring all our tools with us in clinical care and health assessment. The most important are the skills to question “received wisdom”, to observe with an open mind, and to appreciate the uniqueness of circumpolar peoples.

Disclosure statement

No potential conflict of interest was reported by the author(s).