The Number of Patients and Therapeutic Profile of Spinal Stenosis Using Health Insurance Claims in Japan.

STUDY DESIGN: Population-based retrospective descriptive study. OBJECTIVE: To describe the number and therapeutic profile of patients with spinal stenosis at a large-scale community level using health insurance claims data. SUMMARY OF BACKGROUND DATA: A few reports have documented the prevalence of spinal stenosis, and no report has described the therapeutic profile for spinal stenosis in a population base. METHODS: We studied the claims data of National Health Insurance and Late-stage Elderly Health Insurance in a prefecture in Japan from April 2010 to March 2011. We considered patients to have spinal stenosis if their claims included at least one diagnosis coded as spinal stenosis for at least 1 month during the study period. Disease criteria were based on the International Classification of Diseases, 10th version. We then described the number and the therapeutic profile of the patients with spinal stenosis by age and sex. RESULTS: Of 699,723 beneficiaries, 52,889 patients with spinal stenosis were identified. The number of patients with spinal stenosis per 1000 beneficiaries was 76, and those for the subgroups of age ≥ 65 years, ≥ 75 years, and ≥ 85 years were 128, 155, and 152, respectively. The number of patients per 1000 beneficiaries showed unimodal distribution, and the peak for males was 191 between the ages 95 to 99 years and that for females was 160 between the ages 80 to 84 years. Analgesics, prostaglandin E1, or both were prescribed to 40%, 2%, or 20% of patients with spinal stenosis, respectively. Physical therapy, nerve blocks, and surgery were done for 19%, 8%, and 0.4% of the patients, respectively. Approximately, 33% of patients did not receive any treatment. CONCLUSION: There were a large number of patients with spinal stenosis in elderly people. Most of them received nonsurgical treatments. Health insurance claims data could be a useful source of surveillance for such common diseases as spinal stenosis. LEVEL OF EVIDENCE: 4.

Inelastic vascular prosthesis for proximal aorta increases pulsatile arterial load and causes left ventricular hypertrophy in dogs.

OBJECTIVES: Elastic property of the proximal aorta plays an important role in reducing pulsatile load to the ventricle. When a stiff vascular prosthesis is used for the proximal aorta, the pulsatile load increases. We designed this study to elucidate whether the increase in pulsatile load caused left ventricular hypertrophy. METHODS: We created an ascending aorta-abdominal aorta bypass in 9 dogs with a noncompliant vascular prosthesis. The aortic arch proximal to the left subclavian artery was occluded to direct blood flow into the bypass. Closed chest studies were performed after a median of 139 days (range 45-588) days. We assessed the pulsatile load of the ventricle by calculating characteristic impedance from pressure and flow velocity in the ascending aorta. The left ventricle was weighed, normalized with body weight, and compared with the control group, which had sham operations (7 dogs). RESULTS: Characteristic impedance of the bypassed dogs was 175% higher than the control (0.146 +/- 0.056 vs 0.053 +/- 0.014 mm Hg. s. mL(-1), P =.009), which resulted in wider pulse pressure (57 +/- 11 vs 25 +/- 11 mm Hg, P <.001). No difference was found in arterial resistance, cardiac output, or systolic blood pressure. Left ventricular weight normalized by body weight was significantly heavier in the bypass group (5.61 +/- 0.75 vs 4.15 +/- 0.62 g/kg, P =.001). CONCLUSION: Since there was no increase in arterial resistance, we conclude that the increase in pulsatile load was the cause of left ventricular hypertrophy. A stiff vascular prosthesis used for the proximal aorta may cause left ventricular hypertrophy.