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BackgroundData, particularly ‘big’ data are increasingly being used for research in health. Using data from electronic medical records optimally requires coded data, but not all systems produce coded data.ObjectiveTo design a suitable, accurate method for converting large volumes of narrative diagnoses from Australian general practice records to codify them into SNOMED-CT-AU. Such codification will make them clinically useful for aggregation for population health and research purposes.MethodThe developed method consisted of using natural language processing to automatically code the texts, followed by a manual process to correct codes and subsequent natural language processing re-computation. These steps were repeated for four iterations until 95% of the records were coded. The coded data were then aggregated into classes considered to be useful for population health analytics.ResultsCoding the data effectively covered 95% of the corpus. Problems with the use of SNOMED CT-AU were identified and protocols for creating consistent coding were created. These protocols can be used to guide further development of SNOMED CT-AU (SCT). The coded values will be immensely useful for the development of population health analytics for Australia, and the lessons learnt applicable elsewhere.

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Low serum ferritin is diagnostic of iron deficiency, yet its published lower cut-off values are highly variable, particularly for pediatric populations. Lower cut-off values are commonly reported as 2.5th percentiles, and is based on the variation of ferritin values in the population. Our objective was to determine whether a functional approach based on iron deficient erythropoiesis could provide a better alternative. Utilizing 64,443 ferritin test results from pediatric electronic health records, we conducted various statistical techniques to derive 2.5th percentiles, and also derived functional reference limits through the association between ferritin and erythrocyte parameters: hemoglobin, mean corpuscular volume, mean cell hemoglobin concentration, and red cell distribution width. We find that lower limits of reference intervals derived as centiles are too low for clinical interpretation. Functional limits indicate iron deficiency anemia starts to occur when ferritin levels reach 10 µg/L, and are largely similar between genders and age groups. In comparison, centiles (2.5%) presented with lower limits overall, with varying levels depending on age and gender. Functionally-derived limits better reflects the underlying physiology of a patient, and may provide a basis for deriving a threshold related to treatment of iron deficiency and any other biomarker with functional outcomes.

After-hours access to general practice (GP) is critical to supporting accessibility and reducing emergency department demand. To understand who utilises after-hours GP services, this study examined the characteristics of presentations to an Eastern Melbourne after-hours clinic between 2005 and 2014. Descriptive analyses of patient and presentation characteristics, diagnoses, medications and pathology were conducted. Across the study period, 39.1% of presentations to the clinic (N=64,800) were by patients under 18 years of age. Females were found to attend more often than males, and nearly 79% of patients attended only once. The most common diagnoses were respiratory system diseases (13.4%), gastrointestinal system diseases (12.6%) and eye and ear problems (11.6%). Antibacterial medications accounted for over half (53.0%) of all prescriptions, with 34% of antibiotics prescribed to patients under 18 years of age. Seasonal variation in GP demand was also observed. Presenting patients differed from the wider GP patient population, with more young patients, and a higher proportion of prescriptions for antibacterial medications compared to other predominantly non-after-hours practices. Further research is required to understand the health-seeking, decision-making of patients who utilise after-hours GPs over predominantly non-after-hours primary care services, to inform service promotion and delivery strategies.