Purpose <p>Home sleep apnoea test (HSAT) is an effective diagnostic test for obstructive sleep apnoea (OSA). However, a proportion of patients who undergo HSAT may obtain an inconclusive result and require further diagnostic testing. Our objective is to evaluate the proportion of patients who have an inconclusive HSAT and complete diagnostic testing with an in-laboratory polysomnogram.</p> Methods <p>Patients who had HSAT performed for suspected OSA and obtained an inconclusive test (technically inadequate study or low pAHI less than 5) were included. Rates of completion of diagnostic testing, factors associated with completion of diagnostic testing and rates of OSA in patients who completed diagnostic testing were evaluated.</p> Results <p>139 patients (106 male and 33 female, age 38 ± 27, body mass index 25.6 ± 7.9&#xa0;kg/m²) with inconclusive HSAT were included. Only 35 patients (25.2%) completed diagnostic testing after the inconclusive HSAT. Multivariate analysis showed male gender, individuals at elevated risk of moderate to severe OSA and those who were previously counseled about the need for repeat testing had significantly higher odds of completing diagnostic testing. 20 out of 35 patients (57%) who completed diagnostic testing had moderate to severe OSA.</p> Conclusion <p>A considerable percentage of patients with an inconclusive HSAT failed to complete diagnostic testing, which puts them at risk of missing out on a diagnosis of OSA and potential treatment. Physicians should be aware of this limitation when choosing a diagnostic test for suspected OSA.</p>