Using utilisation data to estimate future demand for medical internists: the impact of demographic demand driver in Thailand.

The demand for medical doctors can be estimated in many ways. The most challenging approach is the model based on population demand and anticipated contextual factors. The eighth national medical education meeting of Thailand in 2009 called for the need to estimate future demand for medical specialists in Thailand to proper plan for postgraduate trainings of royal colleges of medical specialists. This research was to estimate future demand for medical internists in 2021 in Thailand using utilisation data as the proxy of population demand for medical care. Inpatient data of 2009 from the universal coverage and the civil servant medical benefit schemes were grouped into the Thai diagnosis related group version 5. Age-sex specific utilisation rates by DRG or Major Diagnostic Category (the first two digits of DRG) were matched to the workloads of the specialists in internal medicine. Assumptions were made for comprehensively predicting the demand. Different proportions of time were allocated to fulfill inpatient care, outpatient consultations, academic meetings and administrative function for doctors at community hospitals, general hospitals and regional hospitals including teaching activities for doctors at teaching hospitals. The population pyramid of 2021 was used to forecast future demand taking account of casemix utilisation by each age-sex stratum in 2009. The results show the effects of demographic changes on the number of internists needed. Female reproductive age adults in 2021 need fewer internists than female reproductive age adults in 2009. The elderly in 2021 need an additional of 60 to 70 percent more internists than the elderly of 2009. Overall demands for the internists increase 34 percent over 12 years, while the growths of the population over 14 years and of the elderly populations are 11 and 64 percent respectively. Further fine-tuning of the model for forecasting demand for subspecialty especially the gerontologist is warranted to check for consistency of distribution of subspecialties within the internal medicine. Future policy research is needed for managing production and distribution of the required medical specialists according to needs in different geographical areas.