Investigation of the Existence of Supplier-Induced Demand in use of Gastrostomy Among Older Adults

The aim of this study is to clarify whether there is small area variation in the use of gastrostomy that is explained by hospital physician density, so as to detect the existence of supplier-induced demand (SID). The study design is a retrospective cohort using claim data of Fukuoka Late Elders’ Health Insurance, submitted from 2010 to 2013. Study participants included 51,785 older adults who had been diagnosed with eating difficulties. We designated use of gastrostomy as an event. Multilevel logistic analyses were then used to investigate the existence of SID. After controlling for patient factors, we found significant regional level variance in gastrectomy use (median odds ratio [MOR]: 1.72, 1.37– 2.51). Hospital physician density was significantly positively related with gastrostomy (adjusted OR of hospital physician density: 1.75, 1.25–2.45; P< 0.001). MORs were largely reduced for the input variable of hospital physician density. We found that the small area variation in use of gastrostomy among older adults could be explained by hospital physician density, which might indicate the existence of SID. (Medicine 95(5):e2519) Abbreviations: AIC = Akaike information criterion, CCI = Charlson comorbidity index, CVA = cerebrovascular accident, FY = fiscal year, ICC = intraclass correlation coefficient, ICD-10 = International Disease Classification 10th revision, MOR = median odds ratio, OR = odds ratio, SID = supplier-induced demand, STM = secondary tier of medical care. INTRODUCTION A fter peaking in 2008, the Japanese population as a whole has been decreasing; however, the older population has been consistently increasing. The proportion of adults>65 years old in o, MD, MS, PhD, T MPH, Yumi Harano, MD infections such as pneumonia are prevalent among older adults, as a result of cumulative molecular and cellular damage. These conditions consequently induce difficulty with intake of adequate nutrition. Gastrostomy for feeding has been commonly used among this population. The All Japan Hospital Association reported there were an estimated 260,000 older adults in Japan with a surgically implanted feeding tube. However, several studies have found that gastrostomy for older patients, particularly those with advanced dementia, was not associated with prevention of aspiration, recovery from pressure ulcers, or lower mortality. The Japan Geriatrics Society recently issued a guideline recommending gastrostomy for older adults with eating difficulties only after consideration of whether it would contribute to an improved prognosis or quality of life. However, it has been reported that the proportion of older patients who were evaluated for swallowing ability before feeding tube placement was as low as 22.9%, which suggests that preevaluation and indications for gastrostomy might not be appropriate. It is well known that gastrostomy feeding tube insertion was relatively profitable in Japan before revision of the national fee schedule in 2014, approximately 1000 USD (100 JPY1⁄4 1