Introduction: There is sparse evidence in the literature in relation to the chest computed tomography (CT) findings among adult Indigenous Australians with chronic respiratory conditions. Methods: In this retrospective study, patients who underwent chest CT between 2012 and 2020 among those referred to undergo lung function tests (spirometry) were assessed for the prevalence of abnormal chest CT radiological findings. Results: Of the 402 patients (59% female) included in this study, 331 (82%) had an abnormality identified on chest CT. Most abnormalities occurred alongside one (25%) or multiple (46%) other CT abnormalities. Airway disease ((AD) (including, emphysema, airway wall thickening and small airway disease) (35%), atelectasis: segmental or lobar collapse (27%), inflammatory opacities (24%) and bronchiectasis (23%) were the most common findings. AD and bronchiectasis were also the most common concurrent abnormalities in 40-50%. Other CT abnormalities noted in isolation or in combination with other CT findings were lung nodules (19%), lymph node enlargement (17%), consolidation or mass (17%), followed by lung cysts, ground-glass opacity, lung parenchymal architectural distortion, cavitating lung lesions and chronic pleural effusion were observed in ≤10%. Predictive models for odds of abnormality and outcomes showed age, smoking and underweight were associated with AD, and male sex and very remote residence were associated with bronchiectasis. Conclusion:This study has illustrated that Indigenous Australian adults have a high prevalence of multiple chest CT abnormalities that may impose unprecedented diagnostic and therapeutic challenges in this population. Further studies are warranted to determine the long-term implications and prognostic significance of the CT findings as demonstrated in this study.

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The response to ACTH stimulation, insulin-hypoglycemia and metyrapone in patients with suspected HPA axis dysfunction due to corticosteroid therapy (Group I, n = 10), or pituitary surgery (Group II, n = 7) and in a control population (Group III, n = 8) was studied. Group I patients had been maintained on a stable low dose of prednisone 5.0-7.5 mg/day for 1 month-16 yr (mean = 31 mos) prior to testing. Basal 08:00 h cortisol levels in this group were not different from control values. However, the mean responses to all three testing procedures were suppressed (Group I vs III, ACTH p less than 0.001, insulin p less than 0.01, metyrapone p less than 0.05). Group II patients had undergone surgery 1-26 months (mean = 10 mo) prior to testing and had been maintained subsequently on a stable dose of prednisone 5.0-7.5 mg/day. In this group basal mean 08:00 h cortisol and the cortisol response to ACTH and insulin-hypoglycemia were not significantly different from control values while the response to metyrapone was suppressed (Group II vs III p less than 0.02). Basal serum DHEA-S levels were suppressed in both Groups I and II when compared to Group III (p less than 0.001). Discordant responses to the three testing procedures were noted in 6 patients with suspected HPA dysfunction with abnormal test results in 1/6 using cortrosyn, 3/6 using insulin-hypoglycemia and 4/6 using metyrapone.(ABSTRACT TRUNCATED AT 250 WORDS)

Background Studies assessing normative values and sex differences in pulmonary function test parameters (PFTPs) among Indigenous populations are sparse. Methods PFTPs were compared between male and female Indigenous Australian adults with and without chest radiologically proven chronic airway diseases (CADs). Results 485 adults (56% were female) with no significant difference in age, body mass index or smoking status between sexes were included. Females displayed a higher prevalence of radiology without CADs compared to males (66 vs. 52%, respectively). Among patients without CADs, after adjustment for age, stature and smoking, males displayed significantly higher absolute values of Forced Vital Capacity (FVC) (mean difference, 0.41L (0.21,0.62), p<0.001) and Forced Expiratory Volume in one second (FEV1) (mean difference 0.27L (0.07,0.47), p<0.001), with no significant difference in FEV1/FVC ratio (mean difference -0.02 (-0.06, 0.02), p = 0.174). Male and female patients with radiologically proven CADs demonstrated lower FEV1/FVC values. However, compared to females, males showed significantly greater reductions in pre- [-0.53 (-0.74, -0.32) vs. -0.29 (-0.42, -0.16), p = 0.045] and post- [-0.51 (-0.72, -0.3) vs. -0.27 (-0.39, -0.14), p = 0.049] bronchodilator FEV1. Conclusions There are significant sex differences in the PFTPs among Indigenous Australians. Recognising these differences may be of value in the accurate diagnosis, management, monitoring and prognostication of CADs in this population.