Equal measurement, not just equal access

A decade of chest imaging that found the ruler itself was wrong

Most conversations about Indigenous health equity are about access — who can reach a scanner, how far the nearest hospital is, whether a service exists at all. That conversation matters, and I have spent much of my career in the rural and remote parts of it. But a body of imaging research I have contributed to over the past decade points at a quieter, more uncomfortable problem: even when an Aboriginal or Torres Strait Islander patient does reach the scanner, the tools we use to interpret what we find were built on somebody else’s body.

This is the through-line of seven peer-reviewed papers, produced with the Darwin respiratory research group, in which I provided the diagnostic chest imaging. Read together, they make a single argument: for Indigenous respiratory health, the reference standards are part of the disease burden.

The measurement was calibrated on the wrong population

The clearest example is lung function. When we compared the spirometry of Australian Aboriginal adults with matched non-Indigenous adults — all with normal chest radiology, all ‘apparently healthy’ — the Aboriginal group recorded values roughly twenty per cent lower for the two headline measures of lung capacity, and the difference held after accounting for age, height, weight, sex and smoking [7]. Crucially, the international GLI-2012 reference equations that clinics use every day did not fit this population under any of their ethnicity settings, including the ‘other/mixed’ option. A healthy Aboriginal adult scored as abnormal simply because the reference curve had never been drawn for them.

When the ruler is calibrated on the wrong population, a healthy person is told they are sick — and a sick person is told they are fine.

That is not an academic footnote. Reference values decide who gets diagnosed, who gets treated, who qualifies for a subsidised medicine, and who is reassured and sent home. A miscalibrated norm produces error in both directions at once.

The disease is more common, more severe, and arrives younger

The imaging told a consistent story about burden. In a series of more than 400 Indigenous adults referred for lung function testing, four in five had an abnormality on chest CT, most often airway disease and bronchiectasis, and abnormalities usually travelled in clusters rather than alone [5]. Very remote residence was an independent predictor of bronchiectasis [5] — geography written directly into the lungs. In the dedicated bronchiectasis imaging cohort, the median age was just 47 [3]: this is disease presenting a generation earlier than the textbooks expect, with disease patterns and severity that differ from the global cohorts on which management guidelines are based [1].

So we built the missing tools

Documenting a gap is easy; the harder and more useful work is closing it. The later papers do exactly that. We characterised the specific radiological signature of bronchiectasis in this population so that a CT severity scale could be built for it rather than borrowed from elsewhere [3], and then proposed one — the Indigenous Bronchiectasis Assessment Scale (IBAS), a severity tool corrected for Indigenous reference values that predicts five-year mortality and hospitalisation [2]. We also showed that lung function differs by sex within the Indigenous population [4], because a single correction factor applied to everyone would simply repeat the original mistake at a coarser grain. The through-line ends in a 2025 call to action arguing that bronchiectasis in Aboriginal adults has been neglected for decades and now demands targeted investment, precisely because its mortality and economic cost are so high [1].

Why this is a health-economics argument too

Getting measurement right is not only fairer, it is cheaper. Mis-classification is expensive in both directions — it funds treatment and follow-up for people who were well, and it withholds early, low-cost intervention from people who were quietly deteriorating until they arrive as an emergency admission. Disease that presents at 47 rather than 67 is two decades of avoidable hospitalisation, and remote bronchiectasis carries some of the highest admission and mortality costs in the system [1]. A validated, population-appropriate severity tool is the sort of small, unglamorous piece of infrastructure that lets a health service direct its scarce resource to the people most likely to benefit. Equity and efficiency, here, point the same way.

My part in this is the imaging — the chest CT and the radiological characterisation that the lung-function and outcome work is built on. It sits alongside the rest of my career in rural and regional radiology, and it is the work I am most proud of, because it makes a specific, testable claim that the profession can act on: for Indigenous respiratory health, equal access to a scan is necessary but not sufficient. We also owe patients a scan that is read against the right standard.

The publications behind this brief

• [1] Heraganahally SS, Howarth T, Heraganahally S, Duncan D, Chen W, Ford PL, Sorger L, Barry S, Burr L. Turning the tide on bronchiectasis in adult Aboriginal Australians: from neglect to action. Intern Med J. 2025;55(9):1578–1582. DOI 10.1111/imj.70116.
• [2] Howarth T, Sorger L, Ben Saad H, Ford PL, Heraganahally SS. Indigenous bronchiectasis assessment scale — the ‘IBAS’. Intern Med J. 2025;55(10):1701–1711. DOI 10.1111/imj.70118.
• [3] Heraganahally SS, Howarth T, Gibbs C, Heraganahally S, Sorger L. Chest CT findings among adult Aboriginal Australians with bronchiectasis in the Top End Northern Territory. J Med Imaging Radiat Oncol. 2024;68(5):545–552. DOI 10.1111/1754-9485.13671.
• [4] Heraganahally SS, Howarth T, Sorger L, Ben Saad H. Sex differences in pulmonary function parameters among Indigenous Australians with and without chronic airway disease. PLOS ONE. 2022;17(2):e0263744. DOI 10.1371/journal.pone.0263744.
• [5] Heraganahally SS, Howarth TP, Sorger L. Chest CT findings among adult Indigenous Australians in the Northern Territory. J Med Imaging Radiat Oncol. 2022;66(3):337–344. DOI 10.1111/1754-9485.13295.
• [6] Heraganahally SS, Howarth T, Mo L, Sorger L, Ben Saad H. Critical analysis of spirometric patterns in correlation to chest CT among adult Indigenous Australians with chronic airway diseases. Expert Rev Respir Med. 2021;15(9):1229–1238. DOI 10.1080/17476348.2021.1928496.
• [7] Heraganahally SS, Howarth T, White E, Sorger L, Biancardi E, Ben Saad H. Lung function parameters among Australian Aboriginal ‘apparently healthy’ adults: a GLI-2012 comparative study. Expert Rev Respir Med. 2021;15(6):833–843. DOI 10.1080/17476348.2021.1847649.

Dr Lisa Sorger is a consultant radiologist, healthcare executive, medical administrator, company director and founder of myradiologist.ai. She provided the diagnostic imaging for the research programme described here. Citations were verified against the PubMed bibliographic database.

All views expressed here are my own personal opinions and are not medical advice. General information only — not clinical or financial advice. myradiologist.ai · ABN 29 692 758 115 · ACN 692 758 115