ABSTRACT
Purpose
This study examined regional healthcare disparities’ impact on the secondary fracture risk following spinal fractures, the likeliest secondary fracture types, and associated risk factors.
Materials and Methods
Participants were selected from the Korean National Health Insurance Service Sample Cohort. Secondary fractures were hip, wrist, humerus, spine, ankle, and pelvis fractures six months after the spinal fracture. The medically vulnerable regions were defined using the PARC index. A Cox proportional hazards model was used to examine differences in the secondary fracture.
Results
A total of 1,135 and 2,426 of the participants lived in medically severely-vulnerable and moderately-vulnerable regions, respectively. Among patients who had spinal fractures, those residing in severely-vulnerable areas had 1.16 times higher risk of secondary fractures compared to those residing in medically non-vulnerable areas. Within 25–84 months after spinal surgery, patients in severely-vulnerable regions had 1.28 times higher secondary fracture risk.
Conclusions
Among patients with spinal fractures, those residing in medically vulnerable areas have a higher secondary fracture risk than those living in non-vulnerable areas. Policy measures are crucial for preventing secondary fractures in this population.
KEYWORDS: Spinal fractures, Healthcare disparities, Health inequities, Secondary fracture, Medically vulnerable area
Introduction
As the global population continues to age, osteoporosis is emerging as a pressing public health concern, resulting in approximately 9 million fractures annually worldwide, a figure that is anticipated to increase over time (1, 2). The World Health Organization has identified osteoporotic fractures as among the top 10 most critical global health challenges, estimating that around 40% of women aged ≥50 years will experience osteoporosis-related fractures in their lifetime (1, 3).
Osteoporotic spinal compression fractures are the most common osteoporotic fracture types, affecting more than 1.4 million individuals annually and presenting a substantial challenge for the older adult population (3, 4). Most patients experience sufficient pain relief through conservative treatment, including bed rest, immobilization, pain medication, and bracing (5). For those with persistent pain, minimally invasive spinal surgeries, such as percutaneous vertebroplasty and kyphoplasty, are viable options (6, 7). However, spinal compression fractures and the resulting deformed spinal structures lead to chronic back pain, limited mobility, impaired physical function, reduced quality of life, and higher mortality rates among older patients (8). In addition, these fractures impose both a psychological and an economic burden on patients and the socio-economic and healthcare systems (9). Therefore, refracture treatment and prevention are crucial to improving patients’ quality of life and alleviating the societal burden (10).
Various studies have investigated the refracture occurrence following spinal compression fractures. Individuals with multiple comorbidities affecting bone metabolism, such as chronic liver and kidney diseases, have a higher fracture risk (11). Moreover, factors such as sex, age, bone mineral density (BMD), Cobb ratio, visual analog scale scores, bone cement leakage after percutaneous procedures, and anti-osteoporosis medications have been associated with refracture risk (2). However, studies on these risk factors have been limited to radiological and clinical factors examined post-surgery. To effectively prevent refractures, a multimodal approach is necessary, (9) including strategies such as proper cement injection, vertebral height restoration, anti-osteoporosis therapy implementation, and rehabilitative exercise engagement. Access to medical facilities may be critical for fracture treatment and prevention. However, evidence is limited on this aspect of spinal compression fractures.
Our study aimed to examine whether regional healthcare disparities contribute to an increased secondary fracture risk following spinal fractures. We also aimed to identify the most common secondary fracture types and the secondary fracture risk factors in patients residing in medically vulnerable areas.
Methods
Database
Participants in our study were selected from the National Health Insurance Service-Sample Cohort (NHIS-SC) (12, 13). The NHIS-SC comprises a million people selected by a systematic stratified random sampling method from among 48,222,537 individuals on January 1, 2006. (14). The NHIS created the NHIS-SC dataset to offer researchers representative administrative data concerning healthcare utilization and health examinations for the entire South Korean population from 2002 to 2019. The key variables in the NHIS-SC include all inpatient and outpatient medical claims data, such as codes for treatment procedures, prescriptions, and diagnoses.
Construction of spinal fracture cohort
Based on previous studies, the inclusion criteria for the spinal fracture cohort included one of the following (15-17):
presence of spinal fracture diagnostic codes (International Statistical Classification of Diseases and Related Health Problems, 10th Revision [ICD-10] M484, M485, M495, S220, S221, S320) accompanied by surgical procedure codes (kyphoplasty or vertebroplasty)
primary diagnostic spinal fracture codes with admission to an acute care hospital
primary diagnostic spinal fracture codes with thoracolumbar, lumbar, or lumbosacral radiographic examinations
Patients with histories of hip, wrist, humerus, spine, ankle, and pelvis fractures before January 1, 2004, were excluded to ensure a minimum 2-year fracture-free period. Time zero for a spinal fracture was defined as the first date when claims data met the inclusion criteria. In addition, patients who were diagnosed with spinal fractures within six months after the first spinal fracture were excluded to avoid any possible simultaneous fractures. Secondary fractures were defined as fractures of the hip, wrist, humerus, spine, ankle, and pelvis occurring six months after the spinal fracture.
Medically vulnerable regions
This study examined the impact of residing in medically vulnerable regions, defined using the PARC index (18). This index allowed for the identification of healthcare levels by region in Korea. PARC is an objective indicator that compares regions’ relative healthcare levels using the positioning method. The PARC values range from 1 to −1, where 1 indicates superior healthcare levels in the region, 0 indicates average healthcare levels, and −1 indicates the worst healthcare levels compared to the overall regional average. Therefore, a value closer to −1 indicates a lower healthcare level in the region than the average healthcare level in the entire region, while a value closer to 1 indicates a higher healthcare level than the average healthcare level in the region. For this study, regions with PARC values < −0.33 and > −0.66 were classified as medically moderately vulnerable regions, and severely vulnerable areas were defined as PARC values < −0.66.
Statistical analysis
The primary dependent variable in this study was secondary fractures occurring six months after the first spinal fracture. Secondary fractures included fractures of the hip, wrist, humerus, spine, ankle, and pelvis. The other covariates included age group (<50, 50–59, 60–69, 70–79, 80–89, > 90 years), sex (male/female), household income (low/middle/high), insurance type (health insurance/medical aid), Charlson’s comorbidity index (CCI) (0, 1, 2+), disability (yes/no), number of beds (<100/100–500/500<), and hospital type (tertiary hospital/secondary hospital/general hospital). Medication history three years before the spinal fracture included diabetes mellitus, hypertension, steroid use, and osteoporosis medications.
The chi-squared test was used to compare the study population’s general characteristics. A Cox proportional hazards model was used to examine the regional differences in secondary fractures in the spinal fracture cohort, and an independent subgroup analysis was performed, including all covariates. The results are presented as hazard ratios (HRs) and confidence intervals (CIs). All statistical analyses were performed using SAS version 7.1 Enterprise (SAS Institute, Cary, NC, USA), and all P values were two-sided, with a significance level of 0.05.
Ethical consideration
This study was reviewed and approved by the Eulji University Institutional Review Board (IRB number: EUIRB2023–025) and adheres to the tenets of the Declaration of Helsinki. The NHIS-NSC data do not contain any identifying information, in which additional approval was not required.
Results
Among the total study population (N = 16,914), 1,135 lived in severely vulnerable regions, 2,426 in moderately vulnerable regions, and 13,353 in non-vulnerable regions (Table 1).
Table 1.
General characteristics of the study population according to region.
| Characteristics | Region | P value | |||||
|---|---|---|---|---|---|---|---|
| Severe-Vulnerable Region | Moderate-vulnerable regions | Non-vulnerable regions | |||||
| (N = 1,135) | (N = 2,426) | (N = 13,353) | |||||
| Secondary Fracture | 0.0003 | ||||||
| Yes | 319 | (28.1) | 627 | (25.8) | 3,138 | (23.5) | |
| Humerus Fracture | 6 | (1.9) | 9 | (1.4) | 80 | (2.5) | |
| Pelvis Fracture | 16 | (5.0) | 35 | (5.6) | 143 | (4.6) | |
| Wrist Fracture | 24 | (7.5) | 33 | (5.3) | 231 | (7.4) | |
| Ankle Fracture | 5 | (1.6) | 12 | (1.9) | 103 | (3.3) | |
| Spine Fracture | 230 | (72.1) | 438 | (69.9) | 2,015 | (64.2) | |
| Hip Fracture | 38 | (11.9) | 100 | (15.9) | 566 | (18.0) | |
| No | 816 | (71.9) | 1,799 | (74.2) | 10,215 | (76.5) | |
| Age Group | <.0001 | ||||||
| 50-59 | 84 | (7.4) | 217 | (8.9) | 1,568 | (11.7) | |
| 60-69 | 239 | (21.1) | 516 | (21.3) | 3,025 | (22.7) | |
| 70-79 | 498 | (43.9) | 961 | (39.6) | 5,083 | (38.1) | |
| 80-89 | 281 | (24.8) | 668 | (27.5) | 3,341 | (25.0) | |
| More than 90 | 33 | (2.9) | 64 | (2.6) | 336 | (2.5) | |
| Sex | (0.0) | 0.4953 | |||||
| Male | 278 | (24.5) | 577 | (23.8) | 3,090 | (23.1) | |
| Female | 857 | (75.5) | 1,849 | (76.2) | 10,263 | (76.9) | |
| Household income level | 0.0692 | ||||||
| Low | 347 | (30.6) | 709 | (29.2) | 4,003 | (30.0) | |
| Middle | 301 | (26.5) | 634 | (26.1) | 3,215 | (24.1) | |
| High | 487 | (42.9) | 1,083 | (44.6) | 6,135 | (45.9) | |
| Insurance Type | 0.2148 | ||||||
| Health Insurance | 1,107 | (97.5) | 2,363 | (97.4) | 12,937 | (96.9) | |
| Medical Aid | 28 | (2.5) | 63 | (2.6) | 416 | (3.1) | |
| Charlson Comorbidity Index (CCI) | 0.2059 | ||||||
| 0 | 339 | (29.9) | 663 | (27.3) | 3,924 | (29.4) | |
| 1 | 332 | (29.3) | 694 | (28.6) | 3,744 | (28.0) | |
| 2+ | 464 | (40.9) | 1,069 | (44.1) | 5,685 | (42.6) | |
| Diabetes mellitus | 0.0001 | ||||||
| Yes | 212 | (18.7) | 469 | (19.3) | 2,923 | (21.9) | |
| No | 923 | (81.3) | 1,957 | (80.7) | 10,360 | (77.6) | |
| Hypertension | 0.9119 | ||||||
| Yes | 815 | (71.8) | 1,726 | (71.1) | 9,544 | (71.5) | |
| No | 320 | (28.2) | 700 | (28.9) | 3,809 | (28.5) | |
| Steroid | <.0001 | ||||||
| Yes | 1,002 | (88.3) | 2,124 | (87.6) | 11,279 | (84.5) | |
| No | 133 | (11.7) | 302 | (12.4) | 2,074 | (15.5) | |
| Osteoporosis Medication | 0.0049 | ||||||
| Yes | 758 | (66.8) | 1,587 | (65.4) | 8,410 | (63.0) | |
| No | 377 | (33.2) | 839 | (34.6) | 4,943 | (37.0) | |
| Disability | 0.3275 | ||||||
| Yes | 174 | (15.3) | 419 | (17.3) | 2,192 | (16.4) | |
| No | 961 | (84.7) | 2,007 | (82.7) | 11,161 | (83.6) | |
| Number of Beds | <.0001 | ||||||
| Less than 99 | 410 | (36.1) | 887 | (36.6) | 4,600 | (34.4) | |
| 100-499 | 597 | (52.6) | 1,342 | (55.3) | 7,090 | (53.1) | |
| More than 500 | 128 | (11.3) | 197 | (8.1) | 1,663 | (12.5) | |
| Hospital Type | <.0001 | ||||||
| Tertiary Hospital | 47 | (4.1) | 92 | (3.8) | 781 | (5.8) | |
| Secondary Hospital | 337 | (29.7) | 778 | (32.1) | 4,723 | (35.4) | |
| General Hospital | 751 | (66.2) | 1,556 | (64.1) | 7,849 | (58.8) | |
The two-year cumulative secondary fracture incidence risk (IR) was 9.47% in the severely vulnerable cohort, 9.70% in the moderately vulnerable cohort, and 9.17% in the control cohort; however, the six-year cumulative IR was 32.96% in the severely vulnerable cohort, 29.12% in the moderately vulnerable cohort, and 27.8% in the control cohort (Table 2).
Table 2.
Cumulative incidence of secondary fracture during different culmative time frames.
| Cumulative time frame, Y | Cumulative incidence, %(95% CI) | |||||
|---|---|---|---|---|---|---|
| Severe vulnerable regions | Moderate-vunlerable regions | Non-vunlerable regions | ||||
| 1 | 3.44 | (2.44-4.69) | 3.51 | (2.80-4.34) | 3.23 | (2.92-3.56) |
| 2 | 9.47 | (7.71-11.44) | 9.70 | (8.53-11.10) | 9.17 | (8.65-9.72) |
| 3 | 17.32 | (14.88-19.91) | 14.96 | (13.41-16.60) | 14.41 | (13.74-15.09) |
| 4 | 22.89 | (20.05-25.84) | 20.67 | (18.81-22.59) | 19.15 | (18.36-19.94) |
| 5 | 28.06 | (24.87-31.32) | 24.64 | (22.26-26.76) | 23.76 | (22.87-24.66) |
| 6 | 32.96 | (29.47-36.49) | 29.12 | (26.83-31.44) | 27.80 | (26.82-28.79) |
| 7 | 37.69 | (33.89-41.50) | 33.36 | (30.85-35.88) | 31.69 | (30.62-32.77) |
| 8 | 40.73 | (36.69-44.73) | 36.31 | (33.63-38.99) | 35.44 | (34.26-36.61) |
| 9 | 43.68 | (39.37-47.90) | 40.30 | (37.37-43.21) | 39.02 | (37.74-40.30) |
| 10 | 46.23 | (41.63-50.70) | 44.76 | (41.51-47.96) | 42.15 | (40.76-43.54) |
| 11 | 49.45 | (44.39-54.29) | 48.03 | (44.52-51.45) | 45.40 | (43.86-46.93) |
| 12 | 54.51 | (48.59-60.05) | 51.03 | (47.23-54.70) | 48.37 | (46.66-50.06) |
| 13 | 54.51 | (48.59-60.05)* | 53.12 | (49.02-57.05) | 51.39 | (49.44-53.29) |
| 14 | 54.51 | (48.59-60.05)* | 56.26 | (51.50-60.74) | 54.65 | (52.34-56.90) |
| 15 | 54.51 | (48.59-60.05)* | 60.28 | (52.95-66.82) | 56.34 | (53.67-58.92) |
*There was no development of secondary fracture; between 156 months to 180 months.
During the entire follow-up period, 319 of 1,135 patients in severely vulnerable areas developed secondary fractures in 5,041.4 person-years (IR, 6327.5 cases per 100,000 person-years; 95% CI, 5,687.0–7,040.2 cases per 100,000 person-years), 627 of 2,426 patients in moderately vulnerable areas developed secondary fractures in 11,159.7 person-years (IR, 5,618.4 cases per 100,000 person-years; 95% CI, 6,103.4–9,405.2 cases per 100,000 person-years), and in the control cohort, 3,138 of 13,353 individuals developed secondary fractures in 59,381.4 person-years (IR, 5,284.4 cases per 100,000 person-years; 95% CI, 5,105.9–5,469.2 cases per 100,000 person-years). This difference implies that patients in severely vulnerable areas were 1.16 times likelier to develop secondary fractures than those in non-vulnerable areas (HR: 1.16; 95% CI: 1.03–1.11) (Table 3). Furthermore, 25–84 months after surgery, the secondary fracture risk was 1.28 times higher in patients living in severely vulnerable areas than in those in non-vulnerable areas (HR: 1.28; 95% CI: 1.10–1.50) (Table 3).
Table 3.
Comparable analysis of rate of secondary fracture for the association between regional difference and risk of secondary fracture.
| Exposure | Number of Subjects | Number of Secondary Fracture | Person Years | Incidence rate(95% CI) per 100,000 person years | Hazard Ratio | P value | ||
|---|---|---|---|---|---|---|---|---|
| Full Cohort | ||||||||
| Severe vulnerable Region | 1135 | 319 | 5041.4 | 6327.5 | (5687.0-7040.2) | 1.16 | (1.03-1.30) | 0.0105 |
| Moderate vulnerable Region | 2426 | 627 | 11159.7 | 5618.4 | (6103.4-9405.2) | 1.01 | (0.93-1.11) | 0.1690 |
| Non Vulnerable Region | 13,353 | 3138 | 59381.4 | 5284.4 | (5105.9-5469.2) | 1.00 | ||
| Time from Secondary Fracture | ||||||||
| 0-24 Months | ||||||||
| Severe vulnerable Region | 1135 | 90 | 1907.9 | 4717.1 | (3848.4-5782.0) | 1.00 | (0.86-1.24) | 0.9966 |
| Moderate vulnerable Region | 2426 | 202 | 4119.4 | 4870.7 | (3227.5-7350.5) | 1.02 | (0.88-1.19) | 0.7349 |
| Non Vulnerable Region | 13,353 | 1029 | 22523.8 | 4568.4 | (4301.4-4852.0) | 1.00 | ||
| 25–84 Months | ||||||||
| Severe vulnerable Region | 771 | 180 | 2375.4 | 7577.6 | (6538.7-8787.5) | 1.28 | (1.10-1.50) | 0.0016 |
| Moderate vulnerable Region | 1673 | 317 | 5249.5 | 10094.0 | (7485.7-13611.1) | 1.01 | (0.90-1.14) | 0.7990 |
| Non Vulnerable Region | 9049 | 1604 | 28197.0 | 5688.5 | (5416.5-5974.2) | 1.00 | ||
| Beyond 85 Months | ||||||||
| Severe vulnerable Region | 254 | 49 | 767.5 | 6383.6 | (4887.8-8837.1) | 1.04 | (0.78-1.39) | 0.7518 |
| Moderate vulnerable Region | 574 | 108 | 1794.0 | 7051.7 | (4105.6-12111.8) | 1.00 | (0.81-1.23) | 0.9624 |
| Non Vulnerable Region | 2965 | 505 | 8738.6 | 5778.9 | (5300.5-6300.4) | 1.00 | ||
For secondary spinal fractures, the risk in severely vulnerable areas was more pronounced (HR: 1.24; 95% CI: 1.08–1.41) (Table 4).
Table 4.
Result of the association between regional difference and risk of secondary fracture acccording to fracture types.
| Exposure | Number of Subjects | Number of Secondary Fracture | Person Years | Incidence rate(95% CI) per 100,000 person years | Hazard Ratio | P value | ||
|---|---|---|---|---|---|---|---|---|
| Risk of Spine Fracture | ||||||||
| Severe vulnerable Region | 1135 | 240 | 5041.4 | 4760.5 | (4206.2-5387.9) | 1.24 | (1.08-1.41) | 0.0015 |
| Moderate vulnerable Region | 2426 | 466 | 11159.7 | 4818.0 | (4818.0-7960.5) | 1.08 | (0.98-1.20) | 0.1105 |
| Non Vulnerable Region | 13,353 | 2173 | 59381.4 | 3659.3 | (3510.0-3815.0) | 1.00 | ||
| Risk of Other Fractures* | ||||||||
| Severe vulnerable Region | 1135 | 123 | 5041.4 | 2439.7 | (2046.2-2908.9) | 1.02 | (0.85-1.23) | 0.7696 |
| Moderate vulnerable Region | 2426 | 241 | 11159.7 | 2524.8 | (1769.2-3602.9) | 0.88 | (0.77-1.01) | 0.0856 |
| Non Vulnerable Region | 13,353 | 1400 | 59381.4 | 2357.6 | (2238.2-2483.3) | 1.00 | ||
*Other fracture events include those occurring concurrently with spine fractures and cover the risk of fractures of the humerus, pelvis, wrist, ankle, and hip.
In patients with spinal fractures residing in severely vulnerable areas, factors that increased the secondary fracture risk included female sex (HR: 1.18; 95% CI: 1.04–1.34), age ≥71years (HR: 1.15; 95% CI: 1.00–1.33), those with diabetes mellitus (HR:1.41; 95% CI: 1.08-1.84) and a CCI score >2 (HR: 1.32; 95% CI: 1.11–1.57) (Table 5).
Table 5.
Result of the association between regional difference and risk of secondary fracture according to stratified analysis of sex, age group, diabetes mellitus, osteoporosis medication and CCI.
| Exposure | Number of Subjects |
Number of Secondary Fracture |
Person Years |
Incidence rate(95% CI) per 100,000 person years |
Hazard Ratio |
P value | ||
|---|---|---|---|---|---|---|---|---|
| Sex | ||||||||
| Male | ||||||||
| Severe vulnerable Region | 278 | 52 | 1239.0 | 4196.9 | (3222.1-5466.6) | 1.05 | (0.79-1.41) | 0.6985 |
| Moderate vulnerable Region | 577 | 102 | 2551.5 | 5032.0 | (2941.8-8607.2) | 1.07 | (0.86-1.33) | 0.5312 |
| Non vulnerable Region | 3090 | 445 | 12712.7 | 3500.4 | (3188.7-3842.5) | 1.00 | ||
| Female | ||||||||
| Severe vulnerable Region | 857 | 267 | 3802.4 | 7021.8 | (6248.4-7890.9) | 1.18 | (1.04-1.34) | 0.0094 |
| Moderate vulnerable Region | 1849 | 525 | 8608.2 | 8544.6 | (6746.4-10822.0) | 1.01 | (0.92-1.11) | 0.8233 |
| Non vulnerable Region | 10263 | 2693 | 46668.6 | 5770.4 | (5561.4-5987.2) | 1.00 | ||
| Age | ||||||||
| 50–70 | ||||||||
| Severe vulnerable Region | 368 | 99 | 2199.3 | 4501.3 | (3730.8-5431.0) | 1.18 | (0.96-1.46) | 0.1053 |
| Moderate vulnerable Region | 809 | 212 | 4887.6 | 5558.0 | (3800.2-8128.9) | 1.13 | (0.97-1.31) | 0.1083 |
| Non vulnerable Region | 5053 | 1031 | 28281.0 | 3645.5 | (3435.2-3868.7) | 1.00 | ||
| More than 71 | ||||||||
| Severe vulnerable Region | 767 | 220 | 2842.0 | 7740.8 | (6810.1-8798.5) | 1.15 | (1.00-1.33) | 0.0392 |
| Moderate vulnerable Region | 1617 | 415 | 6727.0 | 8844.4 | (6822.8-11465.2) | 0.97 | (0.87-1.07) | 0.5745 |
| Non vulnerable Region | 8300 | 2107 | 31100.3 | 6774.8 | (6498.9-7062.4) | 1.00 | ||
| Diabetes mellitus | ||||||||
| Yes | ||||||||
| Severe vulnerable Region | 212 | 59 | 789.6 | 7471.5 | (5819.9-9591.7) | 1.41 | (1.08-1.84) | 0.0117 |
| Moderate vulnerable Region | 469 | 109 | 1823.7 | 10464.4 | (6311.9-17348.6) | 1.07 | (0.87-1.31) | 0.4960 |
| Non vulnerable Region | 2993 | 635 | 11903.4 | 5334.6 | (4938.7-5762.1) | 1.00 | ||
| No | ||||||||
| Severe vulnerable Region | 923 | 260 | 4251.7 | 6115.1 | (5434.8-6880.5) | 1.11 | (0.97-1.26) | 0.1089 |
| Moderate vulnerable Region | 1957 | 518 | 9336.0 | 7093.2 | (5585.4-9007.9) | 1.00 | (0.91-1.10) | 0.9318 |
| Non vulnerable Region | 10360 | 2503 | 47478.0 | 5271.9 | (5073.3-5478.2) | 1.00 | ||
| Osteoporosis Medication | ||||||||
| Yes | ||||||||
| Severe vulnerable Region | 758 | 242 | 3244.6 | 7458.3 | (6595.6-8433.9) | 1.18 | (1.03-1.34) | 0.0145 |
| Moderate vulnerable Region | 1587 | 452 | 6891.0 | 8811.7 | (6868.6-11304.6) | 1.01 | (0.91-1.12) | 0.8005 |
| Non vulnerable Region | 8410 | 2262 | 35831.5 | 6312.8 | (6063.9-6572.0) | 1.00 | ||
| No | ||||||||
| Severe vulnerable Region | 377 | 77 | 1796.7 | 4285.5 | (3459.6-5308.5) | 1.11 | (0.87-1.40) | 0.3783 |
| Moderate vulnerable Region | 839 | 175 | 4268.6 | 4937.3 | (3201.9-7613.2) | 1.01 | (0.86-1.19) | 0.8333 |
| Non vulnerable Region | 4943 | 876 | 23549.9 | 3719.7 | (3485.3-3969.9) | 1.00 | ||
| CCI | ||||||||
| 0–1 | ||||||||
| Severe vulnerable Region | 671 | 173 | 3263.8 | 5300.5 | (4585.5-6126.9) | 1.04 | (0.89-1.22) | 0.5779 |
| Moderate vulnerable Region | 1357 | 347 | 6810.2 | 5808.7 | (4331.9-7788.9) | 1.00 | (0.89-1.13) | 0.8974 |
| Non vulnerable Region | 7668 | 1776 | 36718.6 | 4836.7 | (4620.9-5062.6) | 1.00 | ||
| More than 2 | ||||||||
| Severe vulnerable Region | 464 | 146 | 1777.5 | 8213.3 | (7029.9-9596.1) | 1.32 | (1.11-1.57) | 0.0014 |
| Moderate vulnerable Region | 1069 | 280 | 4349.5 | 11224.8 | (8187.6-15388.7) | 1.03 | (0.96-1.17) | 0.6452 |
| Non vulnerable Region | 5685 | 1362 | 22662.7 | 6009.8 | (5705.2-6330.7) | 1.00 | ||
Discussion
The study’s main findings are as follows: first, patients in medically vulnerable areas with spinal fractures had an increased refracture risk of 1.24 times compared to those in non-vulnerable areas. Second, among patients with spinal fractures in medically vulnerable areas, the spinal refracture risk was 1.43 times higher than that of sustaining another fracture. Third, risk factors for refracture among patients with spinal fractures residing in medically vulnerable areas included female sex, age ≥70 years, those with diabetes mellitus and not using osteoporosis medications.
Various studies have reported refracture risk factors, emphasizing factors such as BMD, fracture history, age, sex, and steroid use as primary factors (19). However, most previously reported risk factors for refracture included clinical and medical history characteristics (3). Disparities in the utilization rates of spine augmentation procedures among patients with osteoporotic vertebral compression fractures in the United States have been reported to vary by race, suggesting the role of demographic and socioeconomic factors in healthcare access and health outcomes (6). In addition, as observed by Patel et al., regional variations in the kyphoplasty or vertebroplasty utilization rates among patients with vertebral compression fractures in the United States indicate that treatment choices may vary based on patient preferences and the surgeon’s experience (20). However, these studies have not presented outcomes related to the refracture risk after a spinal fracture.
Furthermore, different factors may be relevant when assessing younger and older populations, whereby the former tend to live in urban environments, whereas the latter may live in rural areas with restricted mobility and access to care (6). This study revealed access to care’s considerable impact on secondary fracture risks. To the best of our knowledge, this is the first study to investigate regional medical disparities in patients experiencing secondary fractures following spinal fractures. Various refracture prevention services exist for patients with osteoporotic fractures, and diverse clinical refracture risk factors are known; nevertheless, prevention methods have thus far been insufficient (19). To help prevent refractures, consistently appropriate medical services are necessary. Balasubramanian et al. conducted a study on 377,561 female Medicare beneficiaries who experienced fractures and reported the cumulative risk of subsequent fractures (21). They found that when the initial fracture occurred in the spine, the subsequent fracture rates within one, two, and five years were 14.1%, 25.5%, and 40.1%, respectively, surpassing the rates for other types of fractures, such as those to the pelvis, humerus, wrist, hip, and ankle. Gehlbach et al.'s global longitudinal study of osteoporosis in women, which involved 51,762 patients with fractures, emphasized that the location of the previous fracture was the strongest predictor of subsequent fractures (22). Specifically, a previous spinal fracture was associated with a 7.3-fold increased risk of subsequent spinal fractures and a 3.5-fold increased risk of hip fractures. Furthermore, it has been reported that even after percutaneous augmentation procedures in patients with spinal fractures (19–27).8% experienced secondary spinal fractures, with 68% of them occurring at adjacent vertebrae (2, 23). Considering that spinal fractures are the most common primary and secondary fractures among patients with osteoporosis (4), they should be prioritized, especially in patients residing in medically vulnerable areas. Recent fractures are the foremost predictors of future osteoporotic fractures, and additional risk factors have been extensively studied (22). As individuals age, their bone mass declines, which accelerates the onset of osteoporosis (2). Consequently, advanced age is a significant risk factor for refracture. Female sex, due to postmenopausal osteoporosis, is also a risk factor for refractures (2). Moreover, women tend to experience a higher frequency of fractures at a younger age than men, and the association between refracture risk and BMD weakens (24–26). In the Dubbo Osteoporosis Epidemiology Study, the likelihood of subsequent fractures doubled in women with non-osteoporotic BMD and tripled in those with osteoporotic BMD compared to the risk of initial fractures (25). It is estimated that 39% of subsequent fractures in women occur in individuals with normal or low bone mass. Furthermore, as diabetes is a significant contributor to fracture risk, its role may be amplified in medically vulnerable areas, highlighting the need for targeted preventive strategies. The effects and side effects of anti-osteoporotic medications vary depending on their type; however, their efficacy in preventing osteoporotic fractures is well established (27). Furthermore, osteoporotic medications are clinically effective for patients who have experienced vertebral or hip fractures, irrespective of their BMD levels (28).
This study had a few limitations. First, due to the limited information available in the National Claims Database, certain factors that could potentially affect the results were not included in the analysis. These factors include patient functional status, rehabilitation protocol, BMD, severity of the index fracture, and utilization of medical services such as long-term care in older adults (29). In addition, the treatment protocols may vary based on the scale of healthcare facilities, including the availability of personnel and equipment, particularly in medically vulnerable areas (30). Furthermore, it is worth noting that approximately 39% of refractures occur in individuals with normal or low bone mass, suggesting the limited predictive capability of BMD for refracture (21). Moreover, it is important to recognize that surgical intervention does not prevent refractures. However, we attempted to control other major confounding factors, such as economic status, insurance type, underlying comorbidities, and the size of the hospital where the treatment was performed. Second, the validity of the PARC index in assessing healthcare disparities in diverse global contexts is yet to be established. Therefore, the outcomes of our study were influenced by social attributes specific to South Korea. Nonetheless, considering the uniformity of the characteristics and complications associated with spine fractures across societies, regardless of demographic or socio-economic disparities, we believe that the main findings of our study can be applied to other communities.
Conclusion
Among patients who have experienced a spinal fracture, those residing in medically vulnerable areas have an increased risk of secondary fractures compared to those residing in non-vulnerable areas. Spinal fractures have the highest risk of refracture. Policy-based support such as transportation, home-based care, and expanded healthcare facilities may help provide adequate medical services aimed at preventing refractures among patients with spine fractures in medically vulnerable areas.
Funding Statement
This research was supported by a grant from the Patient-Centered Clinical Research Coordinating Center (PACEN) funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HC23 C0042) and Soonchunhyang University Research Fund. The funding sources have no involvement.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Conflicts of interest
Authors have no conflict of interests to declare.
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