Mei-Chia Chou1, Jing-Yang Huang2, Yao-Min Hung3, Wuu-Tsun Perng4, Renin Chang5, James Cheng-Chung Wei6. 1. Department of Recreation and Sports Management, Tajen University, Pingtung, Taiwan; Department of Physical Medicine and Rehabilitation, Kaohsiung Veterans General Hospital, Pingtung Branch, Pingtung, Taiwan; Graduate Institute of Bioresources, National Pingtung University of Science and Technology, Pingtung, Taiwan. Electronic address: meeichia@gmail.com. 2. Center for Health Data Science, Chung Shan Medical University Hospital, Taichung, Taiwan; Institute of Medicine, College of Medicine, Chung Shan Medical University, Taichung, Taiwan. Electronic address: wchinyang@gmail.com. 3. Office for Medical Education and Research, Kaohsiung Municipal United Hospital, Kaohsiung, Taiwan; School of Medicine, National Yang Ming University, Taipei, Taiwan; Department of Senior Citizen Service Management, Yuhing Junior College of Health Care and Management, Kaohsiung, Taiwan. Electronic address: ymhung1@gmail.com. 4. Department of Recreational Sport & Health Promotion, National Pingtung University of Science and Technology, Pingtung, Taiwan; Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan. Electronic address: albert8886@hotmail.com. 5. Department of Emergency Medicine, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan; Department of Recreation and Sports Management, Tajen University, Pingtung, Taiwan. Electronic address: rhapsody1881@gmail.com. 6. Division of Allergy, Immunology and Rheumatology, Chung Shan Medical University Hospital Taichung, Taiwan; Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan; Graduate Institute of Integrated Medicine, China Medical University, Taichung, Taiwan. Electronic address: wei3228@gmail.com.
Abstract
BACKGROUND/ PURPOSE: Flat foot can alter the lower limb alignment and cause knee and back pain. To explore the association between flat foot and spinal degeneration. METHODS: By using a claims dataset containing 1 million random samples, individuals with flat foot were identified between January 1, 2000, and December 31, 2013. The study assembled a flat foot group and a matched non-flat foot group. Definition of flat foot was according to International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes. The diagnosis date was defined as the index date for follow-up initiation. The follow-up period was defined as the duration from the index date (or nested index date for controls) to the occurrence of spinal degenerative joint disease (DJD), or December 31, 2013. The primary outcome was record of spinal DJD retrieved from the same database. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs), with the control group as a reference. RESULTS: We identified 13,965 patients (most aged <30 years, 88%); 2793 patients were assigned to the flat foot group and 11,172 individuals to the non-flat foot group matched by age, sex, and index year. The mean follow-up duration was approximately 74 months. In total, 329 (11.78%) patients in the study group and 931 (8.33%) patients in the comparison group developed spinal DJD. The adjusted HR (95% CI) of spinal DJD for study group was 1.423(1.250-1.619) compared with the control. Sensitivity analyses with propensity score match and different scenario about spinal DJD enrollment showed similar results. Subgroup analysis showed that in patients aged >45 years with history of flat foot, the adjusted hazard ratios were 1.434, 3.065, 3.110, and 2.061 in association with spondylosis, intervertebral disc disorder, cervical stenosis, thoracic-lumbar-sacral stenosis, respectively. CONCLUSION: Flat foot was found to be an independent risk factor for subsequent spinal DJD.
BACKGROUND/ PURPOSE: Flat foot can alter the lower limb alignment and cause knee and back pain. To explore the association between flat foot and spinal degeneration. METHODS: By using a claims dataset containing 1 million random samples, individuals with flat foot were identified between January 1, 2000, and December 31, 2013. The study assembled a flat foot group and a matched non-flat foot group. Definition of flat foot was according to International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes. The diagnosis date was defined as the index date for follow-up initiation. The follow-up period was defined as the duration from the index date (or nested index date for controls) to the occurrence of spinal degenerative joint disease (DJD), or December 31, 2013. The primary outcome was record of spinal DJD retrieved from the same database. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs), with the control group as a reference. RESULTS: We identified 13,965 patients (most aged <30 years, 88%); 2793 patients were assigned to the flat foot group and 11,172 individuals to the non-flat foot group matched by age, sex, and index year. The mean follow-up duration was approximately 74 months. In total, 329 (11.78%) patients in the study group and 931 (8.33%) patients in the comparison group developed spinal DJD. The adjusted HR (95% CI) of spinal DJD for study group was 1.423(1.250-1.619) compared with the control. Sensitivity analyses with propensity score match and different scenario about spinal DJD enrollment showed similar results. Subgroup analysis showed that in patients aged >45 years with history of flat foot, the adjusted hazard ratios were 1.434, 3.065, 3.110, and 2.061 in association with spondylosis, intervertebral disc disorder, cervical stenosis, thoracic-lumbar-sacral stenosis, respectively. CONCLUSION: Flat foot was found to be an independent risk factor for subsequent spinal DJD.