Nationwide Population-based Retrospective Cohort Study Research Articles

Vonoprazan versus proton pump inhibitors for postendoscopic submucosal dissection bleeding in the stomach: a multicenter population-based comparative study

The effectiveness of vonoprazan relative to that of proton pump inhibitors (PPIs) after gastric endoscopic submucosal dissection (ESD) is unclear. Although previous studies used post-ESD ulcer healing as the outcome measure, post-ESD bleeding rate is the most objective and appropriate outcome measure because it has less ascertainment bias. We aimed to compare the post-ESD bleeding rates between vonoprazan and PPIs. This nationwide population-based retrospective cohort study was conducted between 2014 and 2018 and involved 9 hospitals. After 2 days of intravenous PPI administration, either vonoprazan or PPI was administrated from postoperative day 2 to30. Overall, data of 1715 patients (627 patient pairs) were analyzed through propensity score matching. The vonoprazan group had significantly lower post-ESD bleeding rates than the PPI group (overall, 11.9% vs 17.2%, P= .008; bleeding between days 2 and 30, 7.8% vs 11.8%, P= .015). The readmission rate because of post-ESD bleeding was lower in the vonoprazan group (2.4% vs 4.1%, P= .081). Blood transfusion (2.1% vs 3.0%, P= .15) and additional surgery because of delayed perforation (.5% vs 1.0%, P= .32) were not significantly different between the 2 groups. No deaths within 30 days occurred in both groups. On Cox regression analysis, vonoprazan use, lesion location (antrum), aspirin use, direct oral anticoagulant use, and Charlson Comorbidity Index (≥2) were associated with an increased risk of post-ESD bleeding within 30 days. Vonoprazan has a lower post-ESD bleeding rate than PPIs. Further prospective studies are required to confirm these results.

Increased non-typhoidal Salmonella hospitalizations in transfusion-naïve thalassemia children: a nationwide population-based cohort study

IntroductionAlthough non-typhoidal Salmonella (NTS) infection usually causes self-limited enterocolitis, several risk factors have been found to predispose individuals to more severe NTS infections. However, few studies have discussed the association between NTS infection and pediatric thalassemia populations.Material and methodsA nationwide population-based retrospective cohort study was conducted using medical records of the selected children from the Taiwan National Health Insurance Research Database. Immunocompromised individuals or patients with a history of transfusion or splenectomy were excluded. One thalassemia patient was matched with four non-thalassemia patients based on their year of birth, sex, and urbanization level.ResultsIn this cohort, 912 patients with thalassemia and 3648 comparison cohort were analyzed. The mean age of NTS hospitalization was 2.0 ± 1.4 in thalassemia cohort and 2.6 ± 2.4 in non-thalassemia cohort. Transfusion-naïve thalassemia children were proved to have a higher rate of NTS hospitalization (6.90 vs 4.11 per 1000 person-year; p = 0.0004) than the non-thalassemia cohort, with an adjusted hazard ratio (HR) of 1.68 (95% confidence interval [CI] = 1.26–2.24).ConclusionOur research shows that transfusion-naïve thalassemia is associated with an increased risk of NTS hospitalization. Further prospective study comparing the incidence and severity of NTS infection among children with and without thalassemia is needed.ImpactPediatric transfusion-naïve thalassemia patients have an 1.68-fold increased risk for hospitalization due to non-typhoidal Salmonella (NTS) infection.This is the first nationwide population-based cohort study based on an extremely large database that shows pediatric transfusion-naïve thalassemia patients have an increased risk for NTS hospitalizations.Besides the previously known risk factors such as extremes of age, sickle cell disease, or immunosuppressing conditions, clinicians must also take thalassemia as a possible risk factor for more severe NTS disease.

Visual impairment increases the risk of dementia, especially in young males in a 12-year longitudinal follow-up study of a national cohort

We investigated the effect of visual impairment (VI) on dementia development in a national cohort. In this 12-year nationwide population-based retrospective cohort study, national data were collected from National Health Insurance Cooperation of South Korea from 2002 to 2017, comprising 799,074 subjects selected from the dementia-free cohort representative of the Korean population. Crude hazard ratios (HRs) as well as age- and sex-adjusted HRs and confidence intervals (CIs) for the development of dementia were estimated using multivariable Cox regression models. VI significantly increased the risk of dementia with a HR of 2.726 (95% CI 2.251–3.300, p < 0.0001) after adjusting for age, sex, and interaction between age, sex, and VI. HR of interaction between VI and age for dementia was 0.539 (95% CI 0.436–0.667, p < 0.0001). In the sensitivity analysis after adjustment for age, sex, household income level, BMI and other comorbidities, VI showed higher risk for all the type of dementia (p < 0.0001). In subgroup analysis of VI, young males showed the highest risk for development of dementia with a HR of 2.687 (95% CI 2.219–3.254, p < 0.0001). VI significantly increased the risk of dementia in the study cohort, and young males with VI appeared to be the most susceptible to the development of dementia.

Incidence of tuberculosis in advanced lung cancer patients treated with immune checkpoint inhibitors – A nationwide population-based cohort study

ObjectivesThe aim of this study was to investigate the risk of TB in advanced non-small cell lung cancer (NSCLC) patients treated with Immune checkpoint inhibitors (ICI) after a platinum-based chemotherapy. Materials and methodsA nationwide population-based retrospective cohort study using National health insurance dataset was designed. Patients who were diagnosed as lung cancer between September 1st, 2017 and August 31st, 2018 in South Korea were selected. Among them, those with NSCLC who initiated a platinum-based chemotherapy within 3 months were finally included and followed up until December 31st, 2018. Patients who received nivolumab, pembrolizumab, and atezolizumab within study period were classified as the ICI group. Cox proportional hazard model with time-varying covariates was used to determine effects of the duration of conventional chemotherapy, ICI, and consecutive use of systemic steroid on TB. ResultsA total of 6335 patients were enrolled with 3568.7 years of total follow-up period. Among them, 899 patients underwent ICI treatment. Within the follow-up period, 15 TB cases were identified in the ICI group (incidence: 2582.5 per 100,000 person-years) and 63 TB cases were found in the conventional chemotherapy group (incidence: 2108.5 per 100,000 person-years). In a multivariable Cox proportional hazard model, treatment with ICI was not a significant risk factor for TB development (hazard ratio (HR): 1.21, 95 % confidence interval (CI): 0.45−3.26,p = 0.700). Instead, prolonged use of steroid was associated with an increased TB risk (HR: 1.91, 95 %CI: 0.89−4.08, p = 0.095), although its statistical significance was dependent on the operational definition of the effect duration. Previous TB history and older age were independent risk factors for TB disease. ConclusionIn this real-world study, additional treatment with ICI did not increase the risk of TB in advanced NSCLC patients who underwent a cytotoxic chemotherapy. However, TB incidence in these patients was high regardless of ICI treatment. ClassificationsSystemic Treatments.

The epidemiology of Guillain-Barré syndrome in Thailand over 13 years (2005-2017): A nationwide population-based retrospective cohort study.

There have been no published studies examining the epidemiology of Guillain-Barré syndrome (GBS) in large populations in Thailand. This study aimed to explore the incidence, patient characteristics, seasonality, treatments, and outcomes of GBS in Thailand. The National Health Security Office (NHSO) provided data on in-patient admission between fiscal year 2005 and 2017. We selected all patients with a primary diagnosis of GBS. We retrieved data regarding the total population from the Department of Provincial Administration. A total of 4521 patients with GBS were included. The median age was 42 years (IQR 22-56), and 61.5% were male. The incidence rate increased from 0.48 to 0.93 per 100 000 population over the 13 years. The incidence was increased with age and a male-to-female ratio of 1.6:1. There was seasonal variation in the rate of admission for GBS, with significantly more patients admitted in rainy vs summer (IRR 1.94, 95%CI 1.80-2.10, P < .001) and winter vs summer (IRR 1.48, 95%CI 1.36-1.60, P < .001). Treatment with IVIg increased from 4.4% to 29.6% (P < .001), whereas plasmapheresis decreased significantly from 4% to 1.32% (P=.017). The mortality rate was 3.5%. Elderly and young adults had a significantly higher mortality rate when compared to children and teenagers (P < .001 and P=.003). The incidence of GBS in Thailand was steady over 13 years and was greater in rainy and winter season. Treatment with IVIg increased while plasmapheresis decreased. Mortality was higher in elderly patients.

Early and long-term prognosis in patients with and without type 2 diabetes after carotid intervention: a Swedish nationwide propensity score matched cohort study

ObjectivesTo investigate early and long-term outcomes after treatment of carotid artery stenosis in patients with type 2 diabetes (T2D) compared to patients without T2D.Design/methodThis observational nationwide population-based retrospective cohort study investigated all T2D patients treated for carotid stenosis registered in the National Swedish Vascular Surgery and the National Diabetes Registries. Data was collected prospectively for all patients after carotid intervention, during 2009–2015. We estimated crude early (within 30-days) hazard ratios (HRs) risk of stroke and death, and long-term HRs risk, adjusted for confounders with 95% confidence intervals (CIs), for stroke and death and major adverse cardiovascular events (MACE) by using inverse probability of treatment weighting matching.ResultsA total of 1341 patients with T2D and 4162 patients without T2D were included; 89% treated for symptomatic carotid stenosis, 96% with carotid endarterectomy. There was an increased early risk, HRs (95% CI), for stroke in T2D patients 1.65 (1.17–2.32), whereas risk for early death 1.00 (0.49–2.04) was similar in both groups. During a median follow-up of 4.3 (T2D) and 4.6 (without T2D), with a maximum of 8.0 years; after propensity score matching there was an increased HRs (95% CI) of stroke 1.27 (1.05–1.54) and death 1.27 (1.10–1.47) in T2D patients compared to patients without T2D. Corresponding numbers for MACE were 1.21 (1.08–1.35).ConclusionsPatients with T2D run an increased risk for stroke, death, and MACE after carotid intervention. They also have an increased perioperative risk for stroke, but not for death.

The Association between Migraine and Abdominal Aortic Aneurysms: A Nationwide Population-Based Cohort Study.

Previous studies have indicated that patients with migraine have a higher prevalence of risk factors known to be associated with cardiovascular diseases. There are also shared epidemiology and molecular mechanisms between migraine and abdominal aortic aneurysm (AAA). We hypothesized that patients with migraine could have an increased risk of AAA. To test this hypothesis, we used the National Health Insurance Research Database (NHIRD) to evaluate whether associations exist between migraine and AAA. The data for this nationwide population-based retrospective cohort study were obtained from the NHIRD in Taiwan. The assessed study outcome was the cumulative incidence of AAA in patients with migraine during a 15-year follow-up period. Among the 1,936,512 patients from the NHIRD, 53,668 (2.77%) patients were identified as having been diagnosed with migraine. The patients with migraine had a significantly higher cumulative risk of 3.558 of developing an AAA 5 years after the index date compared with the patients without migraine. At the end of the 15-year follow-up period, a significantly higher incidence of AAA (0.98%) was observed in the patients with migraine than in those without migraine (0.24%). We revealed an association between the development of migraine and AAA.

246 The association between adenotonsillectomy and alopecia areata in childhood: A nationwide population-based retrospective cohort study

246 The association between adenotonsillectomy and alopecia areata in childhood: A nationwide population-based retrospective cohort study

Adenotonsillectomy may increase the risk of alopecia areata in childhood: A nationwide population-based cohort study

Adenotonsillectomy may increase the risk of alopecia areata in childhood: A nationwide population-based cohort study

Hydronephrosis in patients with cervical cancer is an indicator of poor outcome: A nationwide population-based retrospective cohort study.

Cervical cancer is a common malignancy in women. The presence of hydronephrosis in patients with cervical cancer can be a challenging clinical problem. The appropriate management of these patients and the prediction of their outcomes are concerns among gynecologists, urologists, medical oncologists, radiation oncologists, and nephrologists. We enrolled a total of 2225 patients with cervical cancer over a 12-year period from the nationwide database of Taiwan's National Health Insurance Bureau. Among them, 445 patients had concomitant hydronephrosis. The remaining 1780 patients without hydronephrosis were randomly enrolled as a control group for the analysis of associated factors. The results indicated that the proportions of patients with hypertension, chronic kidney disease, and diabetes were significantly higher in the hydronephrosis group. The hydronephrosis group showed a higher all-cause mortality than the non-hydronephrosis group (adjusted hazard ratio 3.05, 95% confidence interval 2.24–4.15, P < .001). The rates of nephrectomy and stone disease were also significantly higher in the hydronephrosis group. A higher percentage of other cancers was also observed in the hydronephrosis group than in the non-hydronephrosis group (12.36% vs 8.99%, respectively). This study shows that cervical cancer with hydronephrosis may have a higher morbidity and mortality than cervical cancer without hydronephrosis. Other factors such as human papilloma virus vaccination, smoking, and cancer staging need to be further studied.

Prevalence and Medical Resource of Patients with Diabetic Foot Ulcer: A Nationwide Population-Based Retrospective Cohort Study for 2001–2015 in Taiwan

Diabetic foot ulcer (DFU) is one of the common complications of diabetes. DFU can cause a huge medical and financial burden due to infections, compromise the quality of life, and increase the mortality rate in patients. However, the consumption of medical resources for DFU is rarely mentioned. A retrospective cohort study was performed. Data were obtained from the National Health Insurance Research Database of Taiwan, and the prevalence and medical utilization data for DFU in 2001–2015 were extracted, followed by the analysis for high-risk populations. Between 2001 and 2015, there were 7511 new DFU patients. A higher proportion in these patients was male, elderly with a low education level, and low income. Between 2001 and 2015, the prevalence of DFU was 0.5–0.8%, and the number of DFU patients showed stable growth. Every year, 12.6–19.3% and 1.2–7.0% of patients underwent debridement and amputation, respectively. The hospitalization fees increased year on year. Our study showed that the DFU prevalence increased year on year, and the DFU medical expenditure increased. DFU tends to occur in males, patients with low socioeconomic status, low education level, those with multiple comorbidities, and old age. Therefore, DFU care and prevention require the entire healthcare system to jointly formulate a prevention plan.

Taking Sleeping Pills and the Risk of Chronic Kidney Disease: A Nationwide Population-Based Retrospective Cohort Study.

Background: Sleeping disorder has been associated with chronic kidney disease (CKD); however, the correlation between sleeping pills use and CKD has not been investigated in-depth yet. This study elucidated the potential association of sleeping pill use with the risk of CKD and CKD progression to end-stage renal disease (ESRD) requiring dialysis. Methods: This study was based on a population-based cohort that included 209,755 sleeping pill users among 989,753 individuals. After applying the exclusion criteria, 186,654 sleeping pill users and 373,308 nonusers were enrolled to monitor the occurrence of CKD. Using a cumulative daily dose, we analyzed the types of sleeping pills related to the risk of CKD and ESRD. Propensity score matching and analysis using Cox proportional hazards regression were performed with adjustments for sex, age, and comorbidities. Results: Sleeping pill use was related to increased CKD risk after adjusting for underlying comorbidities (adjusted hazard ratio [aHR] = 1.806, 95% confidence interval [CI]: 1.617–2.105, p < 0.001). With the exception of hyperlipidemia, most comorbidities correlated with an increased risk of CKD. Persistent use of sleeping pills after CKD diagnosis increased the risk of concurrent ESRD (aHR = 7.542; 95% CI: 4.267–10.156; p < 0.001). After the subgroup analysis for sleeping pill use, brotizolam (p = 0.046), chlordiazepoxide (p < 0.001), clonazepam (p < 0.001), diazepam (p < 0.001), dormicum (p < 0.001), estazolam (p < 0.001), fludiazepam (p < 0.001), flunitrazepam (p < 0.001), nitrazepam (p < 0.001), trazodone (p < 0.001), zolpidem (p < 0.001), and zopiclone (p < 0.001) were found to have significant correlation with increased CKD risk. Conclusion: Sleeping pill use was related to an increased risk of CKD and ESRD. Further studies are necessary to corroborate these findings.

Atypical Antipsychotics Augmentation in Patients with Depressive Disorder and Risk of Subsequent Dementia: A Nationwide Population-Based Cohort Study

While atypical antipsychotic medications are widely used for treating depressive disorders, their long-term effects on the risk of subsequent dementia have not been studied adequately. To investigate whether the risk of dementia differs according to the use of atypical antipsychotic drugs, and compare the effects of antipsychotic agents on dementia risk in individuals with late-life depressive disorders. A nationwide population-based retrospective cohort study was conducted using data from the National Health Insurance Service-Senior Cohort of South Korea. Atypical antipsychotic dosages were standardized using a defined daily dose, and the cumulative dosage was calculated. Participants were observed from January 2008 to December 2015. Cox proportional hazard regression analysis was used to estimate the hazard ratios. The cohort included 43,788 elderly adults with depressive disorders: 9,901 participants (22.6%) were diagnosed with dementia. Findings showed that atypical antipsychotics were prescribed to 1,967 participants (4.5%). Compared with non-users, users of atypical antipsychotics experienced a significantly higher risk for dementia with an adjusted hazard ratio (aHR) of 1.541 (95% confidence interval [CI], 1.415-1.678). A cumulative dose-response relationship was observed (test for trend, p < 0.0001). Among atypical antipsychotics, risperidone displayed the highest risk for dementia (aHR 1.767, [95% CI, 1.555-2.009]). In this study of elderly individuals with depressive disorders, atypical antipsychotic use was associated with a significantly higher risk of subsequent dementia. Healthcare professionals should be aware of this potential long-term risk. A limitation that should be mentioned is that we could not exclude patients with bipolar depression.

Association between Depression, Antidepression Medications, and the Risk of Developing Type 2 Diabetes Mellitus: A Nationwide Population-Based Retrospective Cohort Study in Taiwan.

The relationship between depression, antidepressant medications (ADMs), and the risk of subsequent type 2 diabetes mellitus (T2DM) development remains controversial. Thus, we investigated this aspect by a population-based retrospective cohort study using the Longitudinal Health Insurance Database 2000 available in Taiwan. This large, observational study included 46,201 patients with depression and a 1 : 1 age- and sex-matched nondepression cohort enrolled between January 1, 2000, and December 31, 2013, and the newly diagnosed T2DM incidence rates were determined. We estimated the effects of depression on T2DM and the cumulative incidence curves by Cox proportional regression hazard models and Kaplan-Meier methods, respectively. We found that 47.97% of the patients with depression did not receive ADM. Among patients with depression who received ADM, 29.71%, 6.29%, 0.05%, 9.65%, and 6.32% received selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAOIs), heterocyclic antidepressants, and other medications, respectively. Patients without ADM treatment had a 39% higher risk of developing T2DM. However, those who received ADM treatment had a significantly lower risk of T2DM development in every treatment category. Depressive disorder treated with ADMs, especially with long-term use, was associated with an 11–48% decrease in the risk of T2DM in all ADM groups; however, heterocyclic antidepressant treatment for shorter periods (<80 days) was not significantly associated with a decreased risk of T2DM. The incidence of T2DM in Taiwan was found to be associated with an a priori history of depression and was inversely correlated with ADM treatment.

Association between Relative Preference for Vegetables and Meat and Cancer Incidence in Korean Adults: A Nationwide Population-based Retrospective Cohort Study

Association between Relative Preference for Vegetables and Meat and Cancer Incidence in Korean Adults: A Nationwide Population-based Retrospective Cohort Study

Association between Exposure to Ambient Air Pollution and Age-Related Cataract: A Nationwide Population-Based Retrospective Cohort Study.

This study aimed to investigate the association between ambient air pollutants and cataracts in the general population aged 50 years or older using data from the Korean National Insurance Service—National Sample Cohort. Cataract patients were defined as those diagnosed by a physician and having undergone cataract surgery. After matching the average concentrations of PM2.5, PM10, NO2, CO, SO2, and O3 in residential areas, the association between quartile level of air pollutants and incidence of cataract was analyzed using a multivariate Cox-proportional hazard risk model. Among the 115,728 participants, 16,814 (14.5%) were newly diagnosed with cataract and underwent related surgery between 1 January 2004, and 31 December 2015. Exposure to PM10, NO2, and SO2 was positively associated with cataract incidence, while O3 was negatively associated. The adjusted hazard ratio (HR) with 95% confidence interval was 1.069 (1.025–1.115) in PM10 and 1.080 (1.030–1.133) in NO2. However, the association between cataract and the quartile of PM2.5 measured during one year in 2015 was not clear. The HR of female participants aged 65 or older was significantly increased according to quartile of air pollutants. We identified exposure to PM10, NO2, SO2, and O3 associated with cataract development in Korean adults aged ≥ 50 years. This information may be helpful for policymaking to control air pollution as a risk factor for eye health.

Higher Hospitalization Rate for Lower Airway Infection in Transfusion-Naïve Thalassemia Children.

Few studies have addressed the risk of infection in transfusion-naïve thalassemia patients. We aimed to investigate whether transfusion-naïve thalassemia population has higher hospitalization rates for lower airway infection-related diseases than non-thalassemia population in children. A nationwide population-based retrospective cohort study was conducted using detailed medical records of the Taiwan National Health Insurance Research Database. Transfusion-naïve thalassemia patients were compared with a matched cohort at a ratio of 1:4. Data of the selected patients were adjusted for age, sex, and related comorbidities. We recorded the frequency of admissions or outpatient clinic visits for patients with a diagnosis of pneumonia or acute bronchitis/bronchiolitis. Based on our results, the hospitalization rates and incidence rate ratios of bronchitis/bronchiolitis and pneumonia for transfusion-naïve thalassemia children were all higher than those for non-thalassemia controls. Therefore, we conclude that transfusion-naïve thalassemia children are more likely to experience lower airway infections and have a higher probability of hospitalization for these conditions.

Clinical and economic impact of intensive care unit-acquired bloodstream infections in Taiwan: a nationwide population-based retrospective cohort study

ObjectivesTo estimate the clinical and economic impact of intensive care unit-acquired bloodstream infections in Taiwan.DesignRetrospective cohort study.SettingNationwide Taiwanese population in the National Health Insurance Research Database and the Taiwan Nosocomial...

Association between abdominal aortic aneurysms and alcohol-related diseases.

Heterogeneous associations exist between alcohol consumption and the initial presentation of cardiovascular diseases (CVDs). Studies regarding the association between abdominal aortic aneurysms (AAAs) and alcohol consumption are still limited and controversial. We hypothesize that patients with alcohol-related diseases are susceptible to AAA formation due to the presence of overlapping epidemiological factors and molecular mechanisms. We aimed to use a nationwide population-based retrospective cohort study to evaluate the association between alcohol-related diseases and AAA.The data were extracted from the National Health Insurance Research Database (NHIRD) in Taiwan. The study outcome assessed was the cumulative incidence of AAA in patients with alcohol-related diseases during a 14-year follow-up period.Our study included 22,878 patients who had alcohol-related diseases; these patients with alcohol-related diseases had a significantly higher cumulative risk of developing AAA 5 years after the index date than did the 91,512 patients without alcohol-related diseases. Patients with alcohol-related diseases also exhibited a significantly increased incidence of AAA compared with the incidence among patients without alcohol-related diseases, according to Cox regression analysis and Fine & Gray's competing risk model (adjusted hazard ratio = 2.379, 95% confidence interval = 1.653 -3.424, P < .001). In addition, male gender, older age, and chronic kidney disease were also associated with an increased risk of developing AAA. An interaction model showed that males with alcohol-related diseases had a 10.4-fold higher risk of AAA than did females without alcohol-related diseases.We observed an association between alcohol-related diseases and AAA even after adjusting for several comorbidities and medications in a nationwide population database.

Effect of referral systems on costs and outcomes after hip fracture surgery in Taiwan

To explore the economic burdens of hip fracture surgery in patients referred to lower-level medical institutions and to evaluate how referral systems affect costs and outcomes of hip fracture surgery. A nationwide population-based retrospective cohort study. All hospitals in Taiwan. A total of 7500 patients who had received hip fracture surgery (International Classification of Disease, 9th Revision, Clinical Modification (ICD-9-CM) diagnostic codes 820.0 ∼ 820.9 and procedure codes 79.15, 79.35, 81.52, 81.53) performed in 1997 to 2013. Total costs including outpatient costs, inpatient costs and total medical costs and medical outcomes including 30-day readmission, 90-day readmission, infection, dislocation, revision and mortality. The patients were referred to a lower medical institution after hip fracture surgery (downward referral group) and 3034 patients continued treatment at the same medical institution (non-referral group). Demographic characteristics, clinical characteristics and institutional characteristics were significantly associated with postoperative costs and outcomes (P < 0.05). On average, the annual healthcare cost was New Taiwan Dollars (NT$)2262 per patient lower in the downward referral group compared with the non-referral group. The annual economic burdens of the downward referral group approximated NT$241 million (2019 exchange rate, NT$30.5 = US$1). Postoperative costs and outcomes of hip fracture surgery are related not only to demographic and clinical characteristics, but also to institutional characteristics. The advantages of downward referral after hip fracture surgery can save huge medical costs and provide a useful reference for healthcare authorities when drafting policies for the referral system.