Increased Healthcare Service Utilizations for Patients with Dementia: A Population-Based Study

Background

The majority of previous studies investigating the health care utilization of people with dementia were conducted in Western societies. There is little information on the economic burden on the healthcare system attributable to dementia in Asian countries. This study thus investigated differences in utilization of healthcare services between subjects with and those without a diagnosis of dementia using Taiwan’s National Health Insurance population-based database.

Methods

This study comprised 5,666 subjects with a dementia diagnosis and 5,666 age- and gender-matched comparison subjects without a dementia diagnosis. We individually followed each subject for a 1-year period starting from their index date to evaluate their healthcare resource utilization. Healthcare resource utilization included the number of outpatient visits and inpatient days, and the mean costs of outpatient and inpatient treatments. In addition, we divided healthcare resource utilization into psychiatric and non-psychiatric services.

Results

As for utilization of psychiatric services, subjects with a dementia diagnosis had significantly more outpatient visits (2.2 vs. 0.3, p<0.001) and significantly higher outpatient costs (US$124 vs. US$16, p<0.001) than comparison subjects. For non-psychiatric services, subjects with a dementia diagnosis also had significantly more outpatient visits (34.4 vs. 31.6, p<0.001) and significantly higher outpatient costs (US$1754 vs. US$1322, p<0.001) than comparison subjects. For all healthcare services, subjects with a dementia diagnosis had significantly more outpatient visits (36.7 vs. 32.0, p<0.001) and significantly higher outpatient costs (US$1878 vs. US$1338, p<0.001) than comparison subjects. Furthermore, the total cost was about 2-fold greater for subjects with a dementia diagnosis than for comparison subjects (US$3997 vs. US$2409, p<0.001).

Conclusions

We concluded that subjects who had received a clinical dementia diagnosis had significantly higher utilization of all healthcare services than comparison subjects.     

Healthcare Service Utilization for Practicing Physicians: A Population-Based Study

Background

Physicians are considered to be the most informed consumers in the use of medical services since they have more information about diseases or medical technology. However, although plenty of researchers have suggested that different medical seeking behavior exists among physicians, very few empirical studies have been conducted to investigate differences in medical utilization between physicians and the general population.

Objective

We explored differences in the utilization of healthcare services between physicians and the general population using a population-based dataset.

Design

A cross-sectional study.

Participants

Data for this study were sourced from the Taiwan Longitudinal Health Insurance Database 2000. We included 1426 physicians and 1426 sex- and age-matched comparison subjects.

Methods

We used Wilcoxon-Mann-Whitney tests to explore differences in variables of healthcare resource utilization between physicians and comparison subjects. We further used Kruskal-Wallis tests to examine differences in variables of healthcare resource utilization between physician practice location and comparison subjects.

Results

We found that physicians had significantly fewer outpatient visits (13.2 vs. 15.7, p<0.001) and significantly lower outpatient costs (US$477 vs. US$680, p<0.001) than comparison subjects. Furthermore, physicians had lower total health service costs than comparison subjects (US$643 vs. US$1066, p<0.001). This indicates that the mean total health service costs in the year 2010 was 1.66-fold greater for comparison subjects than for physicians. We also found that there were significant differences in the mean number of outpatient services (p<0.001), outpatient costs (p = 0.001), inpatients costs (p = 0.018), and total costs (p = 0.001) among office-based physicians, hospital-based physicians, and comparison subjects. Specifically, Scheffe contrast tests showed that office-based physicians had significantly more outpatient visits (19.3 vs.10.7, p<0.001) and significantly higher outpatient costs (US$656 vs. US$402, p<0.001) than hospital-based physicians.

Conclusions

Physicians had less healthcare utilization than comparison subjects. Furthermore, hospital-based physicians had higher inpatient costs and less outpatient services and costs than office-based physicians.     

Increased Urine and Serum Nerve Growth Factor Levels in Interstitial Cystitis Suggest Chronic Inflammation Is Involved in the Pathogenesis of Disease

Objective

Interstitial cystitis/bladder pain syndrome (IC/BPS) is considered a bladder disorder due to localized chronic inflammation. This study investigated the nerve growth factor (NGF) levels in serum and urine in patients with IC/BPS.

Materials and Methods

Thirty patients with IC/BPS and 28 normal subjects without lower urinary tract symptoms were recruited from an outpatient clinic. IC/BPS was diagnosed by frequency, bladder pain, and the presence of glomerulations during cystoscopic hydrodistention. Serum and urine were collected before any treatment was given. Serum NGF and urinary NGF/Cr levels were compared between IC/BPS and the controls.

Results

Urinary NGF levels were significantly higher in patients with IC/PBS (26.3±11.2 pg/ml) than in controls (1.40±0.63 pg) (p = 0.014). After normalization, the urinary NGF/Cr levels were significantly greater in IC/BPS (0.69±0.38 pg/mg) than controls (0.20±0.01, p = 0.011). Relative to the levels in control subjects (1.90±0.38 pg/mL), the mean serum NGF levels were higher in patients IC/BPS patients (3.48±0.55 pg/mL) (p = 0.015). No significant correlation was found between the serum and urinary NGF levels in IC/BPS patients. However, the clinical characteristics and medical co-morbidities did not show significant difference between IC/BPS patients with a higher and lower serum NGF level.

Conclusions

Increased urinary NGF levels in IC/BPS patients suggest that chronic inflammation is involved in this bladder disorder. Increased circulating serum NGF levels were noted in over half of patients with IC/BPS, however, the urinary and serum NGF were not inter-correlated and elevated serum NGF did not relate with clinical features.     

Increased Pro-Inflammatory Cytokines,C-Reactive Protein and Nerve Growth Factor Expressions in Serum of Patients with Interstitial Cystitis/Bladder Pain Syndrome

Objective

The etiology and pathogenesis of interstitial cystitis/bladder pain syndrome (IC/BPS) are unclear. Chronic inflammation is considered the main pathology of IC/BPS. This study measured the serum c-reactive protein (CRP), nerve growth factor (NGF) and pro-inflammatory cytokine/chemokine interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and IL-8 expression in patients with IC/BPS to elucidate the involvement of systemic inflammation in IC/BPS.

Methods

Serum samples were collected from 30 IC/BPS patients and 26 control subjects. The concentrations of serum nerve growth factor (NGF), IL-1β, IL-6, TNF-α, and IL-8 were quantified using a bead-based, human serum adipokine panel kit. Serum C-reactive protein (CRP) was also assessed. Differences of serum CRP, NGF, IL-1β, IL-6, TNF-α, and IL-8 levels between the IC/BPS patients and controls were compared, and correlations between CRP and pro-inflammatory cytokines and chemokine were also evaluated.

Results

The results showed that CRP level (p = 0.031), NGF (p = 0.015) and pro-inflammatory cytokines/chemokine IL-1β, IL-6, TNF-α, and IL-8 levels were significantly higher in the patients with IC/BPS than among controls (all p<0.001). Significant associations were observed between IL-1β and IL-8 (p<0.001), IL-6 and CRP (p = 0.01), IL-6 and IL-8 (p = 0.02), and IL-6 and TNF-α (p = 0.03).

Conclusion

Increased pro-inflammatory cytokines/chemokine (IL-1β, IL-6, TNF-α, and IL-8) expression in the sera of IC/BPS patients implies not only mast cell activation, but also that other inflammatory mediators play important roles in the pathogenesis of IC/BPS. Thus, for some patients, IC/BPS is considered a chronic inflammatory disease.     

Bladder Pain Syndrome/Interstitial Cystitis Is Associated with Hyperthyroidism

Background

Although the etiology of bladder pain syndrome/interstitial cystitis (BPS/IC) is still unclear, a common theme with BPS/IC patients is comorbid disorders which are related to the autonomic nervous system that connects the nervous system to end-organs. Nevertheless, no study to date has reported the association between hyperthyroidism and BPS/IC. In this study, we examined the association of IC/BPS with having previously been diagnosed with hyperthyroidism in Taiwan.

Design

Data in this study were retrieved from the Longitudinal Health Insurance Database. Our study consisted of 736 female cases with BPS/IC and 2208 randomly selected female controls. We performed a conditional logistic regression to calculate the odds ratio (OR) for having previously been diagnosed with hyperthyroidism between cases and controls.

Results

Of the 2944 sampled subjects, there was a significant difference in the prevalence of prior hyperthyroidism between cases and controls (3.3% vs. 1.5%, p<0.001). The conditional logistic regression analysis revealed that compared to controls, the OR for prior hyperthyroidism among cases was 2.16 (95% confidence interval (CI): 1.27∼3.66). Furthermore, the OR for prior hyperthyroidism among cases was 2.01 (95% CI: 1.15∼3.53) compared to controls after adjusting for diabetes, coronary heart disease, obesity, hyperlipidemia, chronic pelvic pain, irritable bowel syndrome, fibromyalgia, chronic fatigue syndrome, depression, panic disorder, migraines, sicca syndrome, allergies, endometriosis, and asthma.

Conclusions

Our study results indicated an association between hyperthyroidism and BPS/IC. We suggest that clinicians treating female subjects with hyperthyroidism be alert to urinary complaints in this population.     

The Humanistic and Economic Burden of Restless Legs Syndrome

Objectives

To evaluate the humanistic and economic burden of a restless legs syndrome (RLS) diagnosis with regard to health-related quality of life, work productivity loss, healthcare resource use, and direct and indirect costs.

Study Design

Self-reported data came from the 2012 National Health and Wellness Survey (NHWS), a large, annual, nationally representative cross-sectional general health survey of US adults.

Methods

RLS patients (n = 2,392) were matched on demographic and health characteristics to Non-RLS respondents via propensity score matching differences between groups were tested with Bivariate and multivariable analyses.

Results

RLS patients had significantly lower health-related quality of life scores: Mental Component Summary (44.60 vs. 48.92, p<.001), Physical Component Summary (40.57 vs. 46.78, p<.001), Health Utilities (.63 vs. .71, p<.001) and higher levels of work productivity loss in the past seven days including absenteeism (8.1% vs. 9.3%, p<.001), presenteeism (26.5% vs. 15.8%, p<.001), and overall productivity loss (30.1% vs. 18.1%, p<.001) as well as general activity impairment (46.1% vs. 29.7%, p<.001). RLS patients had significantly higher healthcare resource use in the past 6 months than non-RLS patients: healthcare provider visits (7.46 vs. 4.42%, p<.001), ER visits (0.45 vs. 0.24, p<.001), and hospitalizations (0.24 vs. 0.15, p<.001). RLS patients also had higher estimated direct and indirect costs than non-RLS patients. Finally, it was found that across outcomes increasing severity is associated with increased economic and humanistic burden for RLS patients.

Conclusions

RLS patients suffer a greater humanistic and economic burden than those without RLS. Moreover as severity increases so does the burden of RLS.     

Cost of Treatment in a US Commercially Insured,HIV-1–Infected Population

Objective

Recent treatment patterns and cost data associated with HIV in the United States are limited. This study assessed first-line persistence and healthcare costs of HIV-1 in patients by treatment line and CD4 cell count.

Methods

MarketScan Commercial Claims and Encounters Database (2007–2011) and Lab Database (2007–2010) were used to construct two HIV-1 cohorts: 1) newly treated HIV-1–infected patients with ≥6 months'' continuous enrollment prior to first third-agent drug claim (Newly Treated Cohort) and 2) CD4 cell count test results (CD4 Measurements Cohort). All patients were ≥18 years old and without hepatitis co-infection. The Kaplan-Meier method was used to measure treatment switch rates. Generalized linear models (gamma distribution, log link) were used to compare healthcare costs by treatment line and CD4 cell count controlling for potential confounders.

Results

Newly treated patients (n = 8,617) had mean age of 41, 82% were male, and 20% had experienced AIDS-defining events at baseline. Over 20% of newly treated patients switched initial treatment regimen within 2 years. Average unadjusted (and covariate-adjusted) total healthcare cost/year was $33,674 ($28,861) for first-line, $39,191 ($35,805) for second-line, and $39,882 ($40,804) for third-line treatment. Covariate-adjusted costs of care on second- and third-line treatments were significantly more expensive than first-line treatment (24% [p<0.001] and 41% [p = 0.006] higher, respectively). The CD4 Measurements Cohort included 803 CD4 measurements (mean age 49, 76% male, 8% experienced an AIDS-defining event). Costs associated with CD4 measurements <100 cells/µL were 92% higher than those with >350 cells/µL (p<0.001). For higher CD4 cell counts, the majority of expenditures were for antiretrovirals (64% of total for CD4 >350 cells/µL).

Conclusions

Despite modern advances in antiretroviral therapy and medical care, direct medical costs of HIV-1–infected patients increase after treatment switch and with lower CD4 counts, consistent with previous costing studies.     

Retention in Care and Outpatient Costs for Children Receiving Antiretroviral Therapy in Zambia: A Retrospective Cohort Analysis

Background

There are few published estimates of the cost of pediatric antiretroviral therapy (ART) in Africa. Our objective was to estimate the outpatient cost of providing ART to children remaining in care at six public sector clinics in Zambia during the first three years after ART initiation, stratified by service delivery site and time on treatment.

Methods

Data on resource utilization (drugs, diagnostics, outpatient visits, fixed costs) and treatment outcomes (in care, died, lost to follow up) were extracted from medical records for 1,334 children at six sites who initiated ART at <15 years of age between 2006 and 2011. Fixed and variable unit costs (reported in 2011 USD) were estimated from the provider’s perspective using site level data.

Results

Median age at ART initiation was 4.0 years; median CD4 percentage was 14%. One year after ART initiation, 73% of patients remained in care, ranging from 60% to 91% depending on site. The average annual outpatient cost per patient remaining in care was $209 (95% CI, $199–$219), ranging from $116 (95% CI, $107–$126) to $516 (95% CI, $499–$533) depending on site. Average annual costs decreased as time on treatment increased. Antiretroviral drugs were the largest component of all outpatient costs (>50%) at four sites. At the two remaining sites, outpatient visits and fixed costs together accounted for >50% of outpatient costs. The distribution of costs is slightly skewed, with median costs 3% to 13% lower than average costs during the first year after ART initiation depending on site.

Conclusions

Outpatient costs for children initiating ART in Zambia are low and comparable to reported outpatient costs for adults. Outpatient costs and retention in care vary widely by site, suggesting opportunities for efficiency gains. Taking advantage of such opportunities will help ensure that targets for pediatric treatment coverage can be met.     

Outpatient Healthcare Settings and Transmission of Clostridium difficile

Background

Recent reports suggest that community-associated Clostridium difficile infection (CDI) (i.e., no healthcare facility admission within 90 days) may be increasing in frequency. We hypothesized that outpatient clinics could be an important source for acquisition of community-associated CDI.

Methods

We performed a 6-month prospective study of CDI patients to determine frequency of and risk factors for skin and environmental shedding during outpatient visits and to derive a prediction rule for positive cultures. We performed a point–prevalence culture survey to assess the frequency of C. difficile contamination in outpatient settings and evaluated the frequency of prior outpatient visits in patients with community-associated CDI.

Results

Of 67 CDI patients studied, 54 (81%) had 1 or more outpatient visits within 12 weeks after diagnosis. Of 44 patients cultured during outpatient visits, 14 (32%) had skin contamination and 12 (27%) contaminated environmental surfaces. Decreased mobility, fecal incontinence, and treatment with non-CDI antibiotics were associated with positive cultures, whereas vancomycin taper therapy was protective. In patients not on CDI therapy, a prediction rule including incontinence or decreased mobility was 90% sensitive and 79% specific for detection of spore shedding. Of 84 clinic and emergency department rooms cultured, 12 (14%) had 1 or more contaminated environmental sites. For 33 community-associated CDI cases, 31 (94%) had an outpatient visit during the 12 weeks prior to onset of diarrhea.

Conclusions

Patients with recent CDI present a significant risk for transmission of spores during outpatient visits. The outpatient setting may be an underappreciated source of community-associated CDI cases.     

Medical Attendance for Lower Urinary Tract Symptoms Is Associated with Subsequent Increased Risk of Outpatient Visits and Hospitalizations Based on a Nationwide Population-Based Database

Introduction

Lower urinary tract symptoms (LUTS), which encompass storage, voiding, and postmicturition symptoms, are highly prevalent and recognized globally. Based on a nationwide population-based database, this study tests the hypothesis that medical attendance for LUTS is associated with a subsequent increase in the number of outpatient visits and hospitalizations, with differences among medical specialties and age groups.

Methods

Participants were selected from a random population sample of approximately one million people as a representative cohort of National Health Insurance (NHI) enrollees in Taiwan. Participants had at least three outpatient service claims with a coding of LUTS during the recruitment period 2001–2004. Both the LUTS group and non-LUTS control group were monitored for subsequent outpatient visits and hospitalizations, excluding LUTS-related healthcare services, for 2 years following the index date. The results were categorized based on medical specialty and age group.

Results

The outpatient visit rates (no. per person-year) and adjusted incidence rate ratios (IRRs) (95% confidence interval (CI) were significantly higher in urology (4.51, 95%CI 4.15–4.91) and gynecology (1.82, 95%CI 1.76–1.89) for the LUTS group. They were also significantly high in other departments, including internal medicine (1.25), general practice (1.13), Chinese medicine (1.77), family medicine (1.19), surgery (1.38), and psychiatry (1.98). Similarly, the hospitalization rate (no. per 1000 person-year) and adjusted IRRs (95% CI) were significantly higher in urology (5.50, 95% CI = 4.60–6.50) and gynecology (1.60, 95% CI = 1.35–1.90), as well as in internal medicine (1.55) and surgery (1.56), but not in psychiatry (1.12). Furthermore, the IRRs differed among 3 age groups.

Conclusions

A significantly higher number of outpatient visits and hospitalizations were observed for individuals with LUTS, compared to the control group, and the effects differed with the advancement of age. This study broadens understanding of LUTS by viewing their impact on healthcare services with multiple and overlapping systems, rather than considering them exclusively as symptoms of traditional diseases of the bladder and urethra.     

Self-Report of Healthcare Utilization among Community-Dwelling Older Persons: A Prospective Cohort Study

Background

Self-reported data are often used for estimates on healthcare utilization in cost-effectiveness studies.

Objective

To analyze older adults’ self-report of healthcare utilization compared to data obtained from the general practitioners’ (GP) electronic medical record (EMR) and to study the differences in healthcare utilization between those who completed the study, those who did not respond, and those lost to follow-up.

Methods

A prospective cohort study was conducted among community-dwelling persons aged 70 years and above, without dementia and not living in a nursing home. Self-reporting questionnaires were compared to healthcare utilization data extracted from the EMR at the GP-office.

Results

Overall, 790 persons completed questionnaires at baseline, median age 75 years (IQR 72–80), 55.8% had no disabilities in (instrumental) activities of daily living. Correlations between self-report data and EMR data on healthcare utilization were substantial for ‘hospitalizations’ and ‘GP home visits’ at 12 months intraclass correlation coefficient 0.63 (95% CI; 0.58–0.68). Compared to the EMR, self-reported healthcare utilization was generally slightly over-reported. Non-respondents received more GP home visits (p<0.05). Of the participants who died or were institutionalized 62.2% received 2 or more home visits (p<0.001) and 18.9% had 2 or more hospital admissions (p<0.001) versus respectively 18.6% and 3.9% of the participants who completed the study. Of the participants lost to follow-up for other reasons 33.0% received 2 or more home visits (p<0.01) versus 18.6 of the participants who completed the study.

Conclusions

Self-report of hospitalizations and GP home visits in a broadly ‘healthy’ community-dwelling older population seems adequate and efficient. However, as people become older and more functionally impaired, collecting healthcare utilization data from the EMR should be considered to avoid measurement bias, particularly if the data will be used to support economic evaluation.     

Healthcare Service Utilization by Patients with Obstructive Sleep Apnea: A Population-Based Study

Objective

Although obstructive sleep apnea (OSA) is not a life-threatening disease, very few studies have compared differences in healthcare service utilization between patients with and those without OSA in an Asian population according to different age groups. This study attempted to investigate differences in healthcare service utilization between patients with and those without OSA in different age groups in Taiwan.

Methods

Sampled subjects and data on their health service utilization were retrieved from the Taiwan Longitudinal Health Insurance Database 2005. We included 568 patients with OSA and 2840 subjects without OSA. Each subject was followed for a 1-year period to evaluate their healthcare resource utilization. Wilcoxon-Mann-Whitney tests were performed to compare differences in healthcare utilization between patients with and those without OSA during the 1-year follow-up period.

Results

As to all healthcare service utilization, patients with OSA had significantly more outpatient visits (30.3 vs. 18.6), outpatient costs (US$1231.2 vs. US$764.8), inpatient days (1.8 vs. 1.2), inpatient costs (US$563.6 vs. US$276.7), and total costs (US$1794.8 vs. US$1041.5) than comparison subjects during the 1-year follow-up period. Moreover, patients with OSA aged 40~49 and 50~59 years respectively incurred 2.11- and 2.02-fold higher total costs compared to patients without OSA. However, patients with OSA aged over 70 years did not have higher total costs compared to those without OSA.

Conclusions

This study found that patients with OSA had greater healthcare service utilization than those without OSA. Additionally, patients with OSA in the 40~49- and 50~59-year age groups had about 2-fold higher total costs of healthcare services than those without OSA.     

Comparison of the Effects of Air Pollution on Outpatient and Inpatient Visits for Asthma: A Population-Based Study in Taiwan

Background

A nationwide asthma survey on the effects of air pollution is lacking in Taiwan. The purpose of this study was to evaluate the time trend and the relationship between air pollution and health care services for asthma in Taiwan.

Methods

Health care services for asthma and ambient air pollution data were obtained from the National Health Insurance Research database and Environmental Protection Administration from 2000 through 2009, respectively. Health care services, including those related to the outpatient and inpatient visits were compared according to the concentration of air pollutants.

Results

The number of asthma-patient visits to health-care facilities continue to increase in Taiwan. Relative to the respective lowest quartile of air pollutants, the adjusted relative risks (RRs) of the outpatient visits in the highest quartile were 1.10 (P-trend  = 0.013) for carbon monoxide (CO), 1.10 (P-trend  = 0.015) for nitrogen dioxide (NO₂), and 1.20 (P-trend <0.0001) for particulate matter with an aerodynamic diameter ≦10µm (PM₁₀) in the child group (aged 0–18). For adults aged 19–44, the RRs of outpatient visits were 1.13 (P-trend = 0.078) for CO, 1.17 (P-trend = 0.002) for NO_2, and 1.13 (P-trend <0.0001) for PM₁₀. For adults aged 45–64, the RRs of outpatient visits were 1.15 (P-trend = 0.003) for CO, 1.19 (P-trend = 0.0002) for NO_2, and 1.10 (P-trend = 0.001) for PM₁₀. For the elderly (aged≥ 65), the RRs of outpatient visits in were 1.12 (P-trend  = 0.003) for NO₂ and 1.10 (P-trend  = 0.006) for PM_10. For inpatient visits, the RRs across quartiles of CO level were 1.00, 1.70, 1.92, and 1.86 (P-trend  = 0.0001) in the child group. There were no significant linear associations between inpatient visits and air pollutants in other groups.

Conclusions

There were positive associations between CO levels and childhood inpatient visits as well as NO₂, CO and PM₁₀ and outpatient visits.     

Care Needs and Clinical Outcomes of Older People with Dementia: A Population-Based Propensity Score-Matched Cohort Study

Objective

To explore the healthcare resource utilization, psychotropic drug use and mortality of older people with dementia.

Design

A nationwide propensity score-matched cohort study.

Setting

National Health Insurance Research database.

Participants

A total of 32,649 elderly people with dementia and their propensity-score matched controls (n=32,649).

Measurements

Outpatient visits, inpatient care, psychotropic drug use, in-hospital mortality and all-cause mortality at 90 and 365 days.

Results

Compared to the non-dementia group, a higher proportion of patients with dementia used inpatient services (1 year after index date: 20.91% vs. 9.55%), and the dementia group had more outpatient visits (median [standard deviation]: 7.00 [8.87] vs. 3.00 [8.30]). Furthermore, dementia cases with acute admission had the highest psychotropic drug utilization both at baseline and at the post-index dates (difference-in-differences: all <0.001). Dementia was associated with an increased risk of all-cause mortality (90 days, Odds ratio (OR)=1.85 [95%CI 1.67-2.05], p<0.001; 365 days, OR=1.59 [1.50-1.69], p<0.001) and in-hospital mortality (90 days, OR=1.97 [1.71-2.27], p<0.001; 365 days, OR=1.82 [1.61-2.05], p<0.001) compared to matched controls.

Conclusions

When older people with dementia are admitted for acute illnesses, they may increase their use of psychotropic agents and their risk of death, particularly in-hospital mortality.     

Biomechanical Analysis of a Newly Developed Shape Memory Alloy Hook in a Transforaminal Lumbar Interbody Fusion (TLIF) In Vitro Model

Objective

The objective of this biomechanical study was to evaluate the stability provided by a newly developed shape memory alloy hook (SMAH) in a cadaveric transforaminal lumbar interbody fusion (TLIF) model.

Methods

Six human cadaveric spines (L1-S2) were tested in an in vitro flexibility experiment by applying pure moments of ±8 Nm in flexion/extension, left/right lateral bending, and left/right axial rotation. After intact testing, a TLIF was performed at L4-5. Each specimen was tested for the following constructs: unilateral SMAH (USMAH); bilateral SMAH (BSMAH); unilateral pedicle screws and rods (UPS); and bilateral pedicle screws and rods (BPS). The L3–L4, L4–L5, and L5-S1 range of motion (ROM) were recorded by a Motion Analysis System.

Results

Compared to the other constructs, the BPS provided the most stability. The UPS significantly reduced the ROM in extension/flexion and lateral bending; the BSMAH significantly reduced the ROM in extension/flexion, lateral bending, and axial rotation; and the USMAH significantly reduced the ROM in flexion and left lateral bending compared with the intact spine (p<0.05). The USMAH slightly reduced the ROM in extension, right lateral bending and axial rotation (p>0.05). Stability provided by the USMAH compared with the UPS was not significantly different. ROMs of adjacent segments increased in all fixed constructs (p>0.05).

Conclusions

Bilateral SMAH fixation can achieve immediate stability after L4–5 TLIF in vitro. Further studies are required to determine whether the SMAH can achieve fusion in vivo and alleviate adjacent segment degeneration.     

Association between Polymorphism of the Vitamin D Metabolism Gene CYP27B1 and HLA-B27-Associated Uveitis. Is a State of Relative Immunodeficiency Pathogenic in HLA B27-Positive Uveitis?

Objective

Polymorphisms of the vitamin D metabolism gene CYP27B1 showed associations with multiple autoimmune diseases. The aim of this study was to investigate a possible association between the rs703842 A>G polymorphism of the CYP27B1 gene and HLA-B27-associated uveitis.

Design

One hundred fifty-nine patients with HLA-B27-associated uveitis, 138 HLA-B27-negative controls and 100 HLA-B27-positive controls were recruited for this retrospective case-control study. Main outcome parameters were genotype distribution and allelic frequencies determined by polymerase chain reaction.

Results

Carriers of the rs703842G allele were found significantly more often in patients with HLA-B27-associated uveitis than in HLA-B27-positive controls (p = 0.03). Between patients and HLA-B27-negative controls no significant difference in the genotype distribution of the rs703842 A>G polymorphism was found (p = 0.97).

Conclusions

Our data suggest that the rs703842 A>G polymorphism may play a role in HLA-B27-associated uveitis.