Increased Proportion of Fusion Surgery for Degenerative Lumbar Spondylolisthesis and Changes in Reoperation Rate: A Nationwide Cohort Study With a Minimum 5-Year Follow-up.

STUDY DESIGN: A retrospective cohort study. OBJECTIVE: The objectives of the present study were to examine the changes in the number of surgeries, surgical methods selected, and reoperation rates between the years 2003 and 2008. SUMMARY OF BACKGROUND DATA: The selection of the appropriate surgical method between decompression-only (D) and decompression plus fusion (DF) represents a challenging clinical dilemma in patients with degenerative lumbar spinal spondylolisthesis. DF is selected in greater than 90% of patients, mostly due to the associated low reoperation rate. However, the outcomes of D have been improved with minimally invasive decompression surgery techniques. METHODS: The Health Insurance Review and Assessment Service database was used to create cohorts of all Korean patients who underwent surgery for degenerative lumbar spinal spondylolisthesis in 2003 (2003 cohort, n = 5624) and 2008 (2008 cohort, n = 11,706). All patients were followed up for at least 5 years. Reoperation was defined as the occurrence of any type of second lumbar surgery during the follow-up period. The probabilities of reoperation were calculated using the Kaplan-Meier method. RESULTS: The number of surgeries increased 2.08-fold in 2008. Patients older than 60 years comprised 38.6% of the 2003 cohort and 52.4% of the 2008 cohort. The proportion of DF surgery was 31.13% in the 2003 cohort but 91.54% in the 2008 cohort. However, the high proportion of fusion surgery failed to reduce the reoperation probability in the 2008 cohort (8.1%) compared with that in the 2003 cohort (6.2%). The cost of DF was US$5264 and that of D was $2719 in 2008. DF decreased the reoperation probability by 1% at the cost of $421/patient in the 2008 cohort. CONCLUSION: The increased proportion of fusion surgery without improvement in reoperation probability in an aging society may be cautiously addressed in deciding future health policies. LEVEL OF EVIDENCE: 4.

Increased Volume of Surgery for Lumbar Spinal Stenosis and Changes in Surgical Methods and Outcomes: A Nationwide Cohort Study with a 5-Year Follow-Up.

OBJECTIVE: Examining spine surgery patterns over time is crucial to provide insights into variations and changes in clinical decision making. Changes in the number of surgeries, surgical methods, reoperation rates, and cost-effectiveness were analyzed for all patients who underwent surgery for lumbar spinal stenosis without spondylolisthesis in 2003 (2003 cohort) and 2008 (2008 cohort). METHODS: The national health insurance database was used to create the 2003 cohort (n = 10,990) and 2008 cohort (n = 27,942). The surgical methods were classified into decompression and fusion surgery. The cumulative reoperation probability between those surgeries was calculated using the Kaplan-Meier method in the 2003 cohort and 2008 cohort. Comparison of the incremental cost-effectiveness ratios showed the additional direct cost of a 1% change in the reoperation probability. RESULTS: The surgical volume increased 2.54-fold in the 2008 cohort. The age-adjusted number of surgeries per 1 million people increased 2.6-fold (from 154 in the 2003 cohort to 399 in the 2008 cohort) in aged patients and 1.9-fold (from 154 in the 2003 cohort to 291 in the 2008 cohort) in patients 20-59 years old in the 2008 cohort. The proportion of fusion surgeries increased from 20.3% in the 2003 cohort to 37.0% in the 2008 cohort. In total, the 5-year reoperation probabilities increased from 8.1% in the 2003 cohort to 11.2% in the 2008 cohort. Fusion decreased the reoperation probability by 1% at the cost of 1,711 U.S. dollars. CONCLUSIONS: The increased numbers of spinal surgeries, fusion surgeries, and surgeries in older patients in a recent cohort were noteworthy. However, the increased surgical volume and fusion surgeries did not reduce the reoperation rate.

Increased Volume of Lumbar Surgeries for Herniated Intervertebral Disc Disease and Cost-Effectiveness Analysis: A Nationwide Cohort Study.

STUDY DESIGN: Retrospective cohort study of a nationwide database. OBJECTIVE: The primary objective was to summarize the use of surgical methods for lumbar herniated intervertebral disc disease (HIVD) at two different time periods under the national health insurance system. The secondary objective was to perform a cost-effectiveness analysis by utilizing incremental cost-effectiveness ratio (ICER). SUMMARY OF BACKGROUND DATA: The selection of surgical method for HIVD may or may not be consistent with cost effectiveness under national health insurance system, but this issue has rarely been analyzed. METHODS: The data of all patients who underwent surgeries for HIVD in 2003 (n = 17,997) and 2008 (n = 38,264) were retrieved. The surgical methods included open discectomy (OD), fusion surgery, laminectomy, and percutaneous endoscopic lumbar discectomy (PELD). The hospitals were classified as tertiary-referral hospitals (≥300 beds), medium-sized hospitals (30-300 beds), or clinics (<30 beds). ICER showed the difference in the mean total cost per 1% decrease in the reoperation probability among surgical methods. The total cost included the costs of the index surgery and the reoperation. RESULTS: In 2008, the number of surgeries increased by 2.13-fold. The number of hospitals increased by 34.75% (731 in 2003 and 985 in 2008). The proportion of medium-sized hospitals increased from 62.79% to 70.86%, but the proportion of surgeries performed at those hospitals increased from 61.31% to 85.08%. The probability of reoperation was highest after laminectomy (10.77%), followed by OD (10.50%), PELD (9.20%), and fusion surgery (7.56%). The ICERs indicated that PELD was a cost-effective surgical method. The proportion of OD increased from 71.21% to 84.12%, but that of PELD decreased from 16.68% to 4.57%. CONCLUSION: The choice of surgical method might not always be consistent with cost-effectiveness strategies, and a high proportion of medium-sized hospitals may be responsible for this change. LEVEL OF EVIDENCE: 4.

The Selection of Open or Percutaneous Endoscopic Lumbar Discectomy According to an Age Cut-off Point: Nationwide Cohort Study.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To provide an age cut-off of percutaneous endoscopic lumbar discectomy (PELD) for optimal reoperation rate with nationwide population-based data. SUMMARY OF BACKGROUND DATA: Open discectomy is the standard operation for lumbar herniated intervertebral disk disease (HIVD). PELD has shown noninferior outcome to open discectomy and there is increasing interest with regard to PELD. However, PELD may not be a suitable option for all age groups. METHODS: We selected 15,817 patients who underwent open discectomy (n = 12,816) or PELD (n = 3001) in 2003 from the Korean Health Insurance Review & Assessment Service (HIRA) database. All patients in the cohort were followed until December 31, 2008, and the minimum follow-up period was 5 years. A time-to-event survival analysis was conducted. The primary endpoint was any type of second lumbar spine surgery during the follow-up period. Minimum P-value approach and a 2-fold cross-validation approach were utilized to determine an age cut-off point. RESULTS: The optimal age cut-off point was determined as 57 years. PELD for older patients (≥57 years) had a higher reoperation risk during the postoperative 3.4 years (hazard ratio [HR] at 1 yr, 1.75; 2 yr, 1.57; and 3 yr, 1.41). However, the reoperation risk was not higher after PELD for patients younger than 57 years, from 1.9 years, than open discectomy (HR at 2 yr, 0.86; 3 yr, 0.78; 4 yr, 0.70; and 5 yr, 0.63). CONCLUSION: In the present study, we showed that an age cut-off point of PELD for optimal reoperation rate may be 57 years, based on nationwide population-based data. The reoperation rate does not seem to be higher for patients younger than 57 years after PELD than after open discectomy; however, PELD for older patients should be applied after careful consideration. LEVEL OF EVIDENCE: 3.

The relationship between diabetes and the reoperation rate after lumbar spinal surgery: a nationwide cohort study.

BACKGROUND CONTEXT: Diabetes is present in 5% to 20% of patients undergoing spine surgeries and is a known risk factor for reoperation. Considering the chronicity of diabetes, its influence on the reoperation rate may differ over time. PURPOSE: To present the relationship between diabetes and the reoperation rate over time. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: A national health insurance database was used to identify a cohort of patients who underwent an initial surgery for lumbar degenerative disease in 2003 (n=34,918). OUTCOME MEASURES: The primary end point was any type of second lumbar surgery after fusion surgery (n=4,792) or decompression surgery (n=30,126) during the early (0-postoperative 90 days), short-term (91-365 days), and midterm (1-6 years) periods. METHODS: All patients were followed up until December 2008. Cox proportional hazards regression modeling was used to assess the adjusted reoperation rates in the diabetic patients. RESULTS: The incidence of diabetes in the present cohort was 24.5% in the fusion group and 16.9% in the decompression group. Overall, reoperation was performed in 13.2% (631 of 4,792) of the patients after fusion surgery and in 14.0% (4,214 of 30,126) of the patients after decompression surgery. After fusion surgery, diabetes did not make a significant difference in the reoperation rate during the entire follow-up period. After decompression surgery, the reoperation rate was not different during Postoperative Month 3, but diabetic patients showed a 1.2 to 1.4 times higher reoperation rate during postoperative 3 months to 5 years (p<.01). CONCLUSIONS: The study did not find a relationship between diabetes at the time of surgery and the reoperation rate during the early postoperative period. Thereafter, the reoperation rate was not higher after fusion surgery in diabetic patients, but it was higher after decompression surgery.

Association between non-adherence to statin and hospitalization for cardiovascular disease and all-cause mortality in a national cohort.

OBJECTIVES: This study evaluates the effect of adherence to stain on hospitalization for cardiovascular disease and all-cause mortality in South Korea. METHODS: We performed a national cohort study on 423,786 individuals using the Korean National Health Insurance Claims Database. The cohort was composed of individuals who were aged between 18 and 84 years, were newly treated with statin, and were followed from 2005 to 2009. Adherence to statin was calculated using medication possession ratio (MPR) and associations between adherence to statin and health outcomes were evaluated using Cox's proportional hazards regression analysis. RESULTS: Of the study subjects, 41.9% were male, 7.4% were beneficiaries of a tax-financed medical aid program (MAP), 1.5% had prior cardiovascular disease (CVD), 13.0% had diabetes, and 27.5% had hypertension. Non-adherence to statin was found to be associated with an increased risk of cardiovascular hospitalization (HR 2.18, 95% CI: 2.02 - 2.35) and all-cause mortality (HR = 1.75, CI: 1.66 - 1.84). As the age of the study group increased, non-adherence was more strongly associated with the risk of hospitalization for CVD. In addition, the risk of hospitalization for CVD was relatively high in patients who were male, older or MAP beneficiaries, and who had hypertension, diabetes, and high Charlson's comorbidity index. CONCLUSIONS: This study supports that non-adherence to statin is associated with an elevated risk of hospitalization for cardiovascular disease and all-cause mortality.

Effect of antihypertensive medication adherence on hospitalization for cardiovascular disease and mortality in hypertensive patients.

Antihypertensive medication treatment is one effective management strategy to prevent cardiovascular disease (CVD) and mortality. However, little research has been conducted on the rates of antihypertensive medication adherence and the effect of antihypertensive medication adherence on health outcomes in South Korea. We searched the Korean National Health Insurance Claims Database for records from 2003 to 2007. Patients in this study were 18 years of age or older and they were diagnosed with hypertension and newly prescribed antihypertensive medication in 2003. Adherence to antihypertensive medication was estimated as the medication possession ratio (MPR). Multivariate Cox regression was used to evaluate the association between medication adherence and adverse health outcomes after adjusting for patient demographics and clinical characteristics. Our study population consisted of 40,408 patients with a mean age of 51 years. Among the patients, 50.3% were men, 4.0% had Medicaid health insurance, 17.8% had diabetes, 20.9% had dyslipidemia and 42.4% were adherent (MPR ≥ 80%). Nonadherent patients (MPR<80%) were younger and more likely to have Medicaid health insurance; they had lower rates of diabetes and dyslipidemia compared with adherent patients. In the Cox multivariate analysis, nonadherence increased the risk of all adverse health outcomes, including all-cause mortality and hospitalization for CVD (hazard ratio: 1.57, confidence interval: 1.40-1.76). In conclusion, our study indicates that medication adherence is important for reducing hospitalization due to CVD and mortality.

Air pollution and asthma among children in Seoul, Korea.

BACKGROUND: As information about the health risks associated with air pollution has become available, attention has focused increasingly on susceptible persons such as children and persons with preexisting respiratory diseases, such as asthma. METHODS: We investigated the association between outdoor air pollution and asthma attacks among children under 15 years of age in Seoul, Korea. We estimated the relative risks of hospitalization associated with an interquartile range (IQR) increase in pollutant concentrations and used time series analysis of the counts by means of the generalized additive Poisson model. RESULTS: The estimated relative risk of hospitalization for asthma was 1.07 (95% confidence interval [CI] = 1.04-1.11) for particulate matters less than or equal to 10 microm in aerodynamic diameter (IQR = 40.4 microg/m3); 1.11 (95% CI = 1.06-1.17) for sulfur dioxide (IQR = 4.4 ppb); 1.15 (95% CI = 1.10-1.20) for nitrogen dioxide (IQR = 14.6 ppb); 1.12 (95% CI = 1.07-1.16) for ozone (IQR = 21.7 ppb); and 1.16 (95% CI = 1.10-1.22) for carbon monoxide (IQR = 1.0 ppm). CONCLUSIONS: These findings support the hypothesis that air pollution at levels below the current standards of Korea is harmful to sensitive subjects such as asthmatic children.