Operative Volumes and Postoperative Outcomes After Elective Resection of Congenital Lung Malformations in Infants.

OBJECTIVE: To determine whether hospital- and surgeon-level operative volumes are associated with differences in postoperative outcomes among infants undergoing elective lung surgery for a congenital lung malformation (CLM). SUMMARY BACKGROUND DATA: Infant lung surgery is a relatively uncommon procedure performed by pediatric surgeons nationwide. The relationship between surgical volume and postoperative outcomes remains unknown. METHODS: A retrospective cohort study of asymptomatic infants who underwent elective lung resection of a CLM was conducted using the Pediatric Health Information System database (2016-2020). Multivariable linear and poisson regressions were performed based on annual lung resection tertiles. RESULTS: There were 1420 infants managed by 48 hospitals and 309 primary surgeons. Institutions that performed seven or fewer CLM resections per year (56%) were associated with significantly higher postoperative complication rates compared to medium- and high-volume hospitals (low: 134 [34%], medium: 110 [21%], high: 144 [29%]; P<0.001). Surgeons who performed one or fewer CLM resections per year (82%) were associated with significantly higher complication rates compared to medium- and high-volume surgeons (low: 171 [31%], medium: 75 [26%], high: 119 [24%]; P=0.02). Multivariable analyses confirmed that low-volume hospitals were associated with higher complications (OR 1.81, CI 1.38-2.37; P<0.001), and low-volume surgeons had an increased risk of complications (overall: OR 1.37, CI 1.01-1.84; P=0.04). CONCLUSIONS: In this cohort study of infants undergoing elective lung resection for a CLM, lower volume providers were associated with higher postoperative patient morbidity. These findings represent an opportunity to inform quality improvement initiatives on pediatric lung resection and the debate on surgical subspecialization for this unique patient population.

Longitudinal Follow-Up of Fibrosis-4 in Patients at Risk of Metabolic Dysfunction-Associated Steatotic Liver Disease Receiving Low-Dose Methotrexate Treatment.

Several noninvasive liver fibrosis tests have been developed and appear to predict the severity of fibrosis, possibly replacing invasive liver biopsy as a monitoring tool.1 The fibrosis-4 (FIB-4) score originally was proposed to help assess liver fibrosis in patients with human immunodeficiency virus and hepatitis C virus co-infection.1 FIB-4 has been used widely to monitor the severity of liver fibrosis, especially in patients with nonalcoholic fatty liver disease,2 now termed metabolic dysfunction-associated steatotic liver disease (MASLD).3.

Identifying the association between serum urate levels and gout flares in patients taking urate-lowering therapy: a post hoc cohort analysis of the CARES trial with consideration of dropout.

OBJECTIVE: To investigate gout flare rates based on repeated serum urate (SU) measurements in a randomised controlled trial of urate-lowering therapy (ULT), accounting for dropout and death. METHODS: We performed a secondary analysis using data from Cardiovascular Safety of Febuxostat or Allopurinol in Patients with Gout, which randomised participants to febuxostat or allopurinol, titrated to target SU <6 mg/dL with flare prophylaxis for 6 months. SU was categorised as ≤3.9, 4.0-5.9, 6.0-7.9, 8.0-9.9 or ≥ 10 mg/dL at each 3-6 month follow-up. The primary outcome was gout flare. Poisson regression models, adjusted for covariates and factors related to participant retention versus dropout, estimated gout flare incidence rate ratios by time-varying SU category. RESULTS: Among 6183 participants, the median age was 65 years and 84% were male. Peak gout flare rates for all SU categories were observed in months 0-6, coinciding with the initiation of ULT and months 6-12 after stopping prophylaxis. Flare rates were similar across SU groups in the initial year of ULT. During months 36-72, a dose-response relationship was observed between the SU category and flare rate. Lower flare rates were observed when SU ≤3.9 mg/dL and greater rates when SU ≥10 mg/dL, compared with SU 4.0-5.9 mg/dL (p for trend <0.01). CONCLUSION: Gout flare rates were persistently higher when SU ≥6 mg/dL after the first year of ULT after accounting for censoring. The spike in flares in all categories after stopping prophylaxis suggests a longer duration of prophylaxis may be warranted.

Gout risk in adults with pre-diabetes initiating metformin.

OBJECTIVE: Despite the strong association between gout and pre-diabetes, the role of metformin in gout among individuals with pre-diabetes remains uncertain. We compared the incidence rates of gout in adults with pre-diabetes starting metformin with those not using antidiabetic treatments. METHODS: We conducted a new-user, propensity score-matched cohort study using electronic health records from an academic health system (2007-2022). Pre-diabetes was defined based on haemoglobin A1c levels. Metformin users were identified and followed from the first metformin prescription date. Non-users of antidiabetic medications were matched to metformin users based on propensity score and the start of follow-up. The primary outcome was incident gout. Cox proportional hazards models estimated the HR for metformin. Linear regression analyses assessed the association between metformin use and changes in serum urate (SU) or C-reactive protein (CRP). RESULTS: We identified 25 064 individuals with pre-diabetes and propensity score-matched 1154 metformin initiators to 13 877 non-users. Baseline characteristics were well balanced (all standardised mean differences <0.1). The median follow-up was 3.9 years. The incidence rate of gout per 1000 person-years was lower in metformin users 7.1 (95% CI 5.1 to 10) compared with non-users 9.5 (95% CI 8.8 to 10.2). Metformin initiation was associated with a reduced relative risk of gout (HR 0.68, 95% CI 0.48 to 0.96). No relationship was found between metformin and changes in SU or CRP. CONCLUSIONS: Metformin use was associated with a reduced risk of gout among adults with pre-diabetes, suggesting that metformin may be important in lowering gout risk in individuals with pre-diabetes.

Disease activity of rheumatoid arthritis and kidney function decline: a large prospective registry study.

INTRODUCTION: Chronic kidney disease (CKD) is a common comorbidity of rheumatoid arthritis (RA). The association of longitudinal RA disease activity with long-term kidney function has remained uncertain. METHOD: We analysed a multicentre prospective RA registry in the USA from 2001 to 2022. The exposure was updated time-averaged Clinical Disease Activity Index (TA-CDAI) categories from study enrolment. The primary outcome was a longitudinal estimated glomerular filtration rate (eGFR) change. Secondary outcomes included developments of CKD stage G3a (eGFR<60 mL/min/1.73 m2) and stage G3b (eGFR<45 mL/min/1.73 m2). Results were adjusted for relevant time-fixed and time-varying covariates. RESULTS: 31 129 patients (median age: 58.0 years, female: 76.3%, median eGFR: 90.7 mL/min/1.73 m2) contributed 234 973 visits and 146 778 person-years of follow-up. Multivariable mixed-effect linear model showed an average annual eGFR decline during follow-up in the TA-CDAI-remission group of -0.83 mL/min/1.73 m2 and estimated additional annual declines (95% CI) of -0.09 (-0.15 to -0.03) in low, -0.17 (-0.23 to -0.10) in moderate and -0.18 (-0.27 to -0.08) mL/min/1.73 m2 in high disease activity patients. Compared with TA-CDAI remission, adjusted HRs (95% CI) for CKD stage G3a during follow-up were 1.15 (1.01 to 1.30) in low, 1.22 (1.06 to 1.40) in moderate and 1.27 (1.05 to 1.52) in high disease activity; for CKD stage G3b, 1.22 (0.84 to 1.76) in low, 1.66 (1.12 to 2.45) in moderate and 1.93 (1.16 to 3.20) in high disease activity. CONCLUSIONS: Higher RA disease activity was associated with accelerated eGFR decline and increased risk of clinically relevant kidney dysfunction. Future intervention studies should attempt to replicate the association between RA disease activity and eGFR.

Changes in alcohol intake and serum urate changes: longitudinal analyses of annual medical examination database.

INTRODUCTION: Despite the established cross-sectional association between alcohol intake and serum urate (SU), its longitudinal association remains unknown. This study aimed to determine whether changes in alcohol intake have a clinically relevant association with SU change. METHOD: We conducted retrospective analyses using systematically collected annual medical examination data from October 2012 to October 2022 in a Japanese preventive medicine centre. The exposure was changes in alcohol intake between two consecutive visits. The association of SU changes with alcohol intake changes was estimated by mixed-effect linear regression with adjustment for relevant covariates. RESULTS: We analysed 63 486 participants (median age, 47.0 years; 55% women; 58.6% regular alcohol drinkers with a median of 1.4 drinks/day) with 370 572 visits. The median SU level was 5.3 mg/dL, and 506 (0.8%) participants had diagnoses of gout or hyperuricemia without medication use during the study period. Decreasing one daily alcohol intake had a clinically small association with SU changes (-0.019 (95% CI: -0.021 to -0.017) mg/dL). Beer had the largest association with SU (-0.036 (95% CI: -0.039 to -0.032) mg/dL for one beer decrease). Complete discontinuation of any alcohol from a mean of 0.8 drinks/day was associated with -0.056 mg/dL (95% CI: -0.068 to -0.043) decrease in SU; the association became larger in hyperuricemic participants (-0.110 mg/dL (95% CI: -0.154 to -0.066) for alcohol discontinuation from a mean of 1.0 drinks/day). CONCLUSIONS: This study revealed changes in alcohol intake had small associations with SU change at the general Japanese population level. Complete discontinuation of alcohol in hyperuricemic participants had only modest improvement in SU.

Earlier vs. later time period of COVID-19 infection and emergent autoimmune signs, symptoms, and serologies.

OBJECTIVE: Autoantibodies and autoimmune diseases after SARS-CoV-2 infection are widely reported. Given evolving variants, milder infections, and increasing population vaccination, we hypothesized that SARS-CoV-2 infection earlier in the pandemic would be associated with more autoimmune connective tissue disease (CTD) symptoms and immunologic abnormalities. METHODS: Patients ≥18 years old with COVID-19 3/1/2020-8/15/2022 completed the CTD Screening Questionnaire and were tested for 27 autoimmune serologies, SARS-CoV-2 serologies, cell-bound complement activation products (CB-CAPs), and T and B lymphocyte immunophenotypes by flow cytometry. We assessed relationships between symptoms, serologies, and immunophenotypes in earlier (3/1/2020-1/31/2021) vs. later (2/1/2021-8/15/2022) periods, with different predominating SARS-CoV-2 viruses. RESULTS: 57 subjects had earlier and 23 had later pandemic COVID-19. 35 % of earlier vs. 17 % of later pandemic patients had CTD symptoms (p 0.18). More patients were antinuclear antibody (ANA) positive (44 % vs. 13 %, p 0.01) and had lupus anticoagulant (11 % vs. 4 %, p 0.67). After adjustment for age, race, and sex, earlier (vs. later) COVID-19 was associated with increased ANA positivity (OR 4.60, 95%CI 1.17, 18.15). No subjects had positive CB-CAPs. T and B cell immunophenotypes and SARS-CoV-2 serologies did not differ by group. In heatmap analyses, higher autoantibody variety was seen among those with infection in the early pandemic. CONCLUSION: In this sample, having COVID-19 infection in the earlier (pre-2/1/2021) vs. later pandemic was associated with more CTD symptoms, ANA positivity, and autoantibody reactivities. Earlier SARS-CoV-2 variants circulating in a less vaccinated population with less natural immunity may have been more immunogenic.

Prevalence and Characteristics of Adults with Difficult-to-Treat Rheumatoid Arthritis in a Large Patient Registry.

OBJECTIVES: An estimated 5-20% of patients with rheumatoid arthritis (RA) fail multiple treatments and are considered "difficult-to-treat" (D2T), posing a substantial clinical challenge for rheumatologists. A European Alliance of Associations for Rheumatology (EULAR) task force proposed a definition of D2T-RA in 2021. We applied EULAR's D2T definition in a cohort of patients with established RA to assess prevalence and we compared clinical characteristics of participants with D2T-RA with matched comparisons. METHODS: Data from the longitudinal Brigham and Women's Hospital Rheumatoid Arthritis Sequential Study (BRASS) registry was used. Participants were classified as D2T if they met EULAR's definition. A comparison group of non-D2T RA patients were matched 2:1 to every D2T patient, and differences in characteristics were evaluated in descriptive analyses. Prevalence rates of D2T were estimated using Poisson regression. RESULTS: We estimated the prevalence of D2T-RA to be 14.4 (95% CI: 12.8-16.3 per 100 persons) among 1,581 participants with RA, and 22.3 (95% CI: 19.9-25.0 per 100 persons) among 1,021 who were biologic/targeted synthetic DMARD experienced. We observed several differences in demographics, comorbidities, and RA disease activity between D2T-RA and non-D2T RA comparisons. Varying EULAR sub-criteria among all participants in BRASS resulted in a range of D2T-RA prevalence rates, from 0.6-17.5 per 100 persons. CONCLUSION: EULAR's proposed definition of D2T-RA identifies patients with RA who have not achieved treatment targets. Future research should explore heterogeneity in these patients and evaluate outcomes to inform the design of future studies aimed at developing more effective RA management protocols.

Longitudinal analysis of serum urate in prediabetic phase.

OBJECTIVES: Despite the well-established association between prediabetes and hyperuricaemia, knowledge about serum urate (SU) trends during the prediabetic phase is limited. Therefore, we aimed to assess the longitudinal changes of SU in individuals with prediabetes. METHODS: Individuals with prediabetes, defined by initial haemoglobin A1c (HbA1c) levels between 5.7% and 6.4%, were identified using electronic health records from an academic health system (2007-2022). We required at least one SU test before and after the prediabetes diagnosis. The primary outcome was the longitudinal SU trends during the follow-up period, estimated with a multivariable mixed-effects model. Patients were censored at diabetes onset. Marginal effects of covariates on SU changes were estimated. Subsequent analyses examined SU variations in subgroups stratified by age, sex, body mass index (BMI), HbA1c, estimated glomerular filtration rate (eGFR) and metformin use. RESULTS: Out of 25 526 individuals with prediabetes, 1,521 met the SU cohort requirements, contributing to 6,832 SU observations. At baseline, median age was 63 years and 40% were female. Median values were SU 6.3 mg/dl, HbA1c 5.9% and BMI 30 kg/m2. Median follow-up was 7.4 years. Older age, male sex, greater BMI, and higher HbA1c were significant predictors of increased longitudinal SU levels. Individuals with a BMI ≥30 kg/m2 exhibited higher SU levels compared with those with lower BMI values. CONCLUSION: Among individuals with prediabetes, several baseline variables were significant predictors of increased SU levels over time. These longitudinal trends in SU, support the potential for early intervention during the prediabetic phase, possibly reducing the risk of gout.

Association of the multi-biomarker disease activity score with arterial 18-fluorodeoxyglucose uptake in rheumatoid arthritis.

OBJECTIVES: Rheumatoid arthritis (RA) and atherosclerosis share many common inflammatory pathways. We studied whether a multi-biomarker panel for RA disease activity (MBDA) would associate with changes in arterial inflammation in an interventional trial. METHODS: In the TARGET Trial, RA patients with active disease despite methotrexate were randomly assigned to the addition of either a TNF inhibitor or sulfasalazine+hydroxychloroquine (triple therapy). Baseline and 24-week follow-up 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography scans were assessed for change in arterial inflammation measured as the maximal arterial target-to-blood background ratio of FDG uptake in the most diseased segment of the carotid arteries or aorta (MDS-TBRmax). The MBDA test, measured at baseline and weeks 6, 18, and 24, was assessed for its association with the change in MDS-TBRmax. RESULTS: Interpretable scans were available at baseline and week 24 for n = 112 patients. The MBDA score at week 24 was significantly correlated with the change in MDR-TBRmax (Spearman's rho = 0.239; p= 0.011) and remained significantly associated after adjustment for relevant confounders. Those with low MBDA at week 24 had a statistically significant adjusted reduction in arterial inflammation of 0.35 units vs no significant reduction in those who did not achieve low MBDA. Neither DAS28-CRP nor CRP predicted change in arterial inflammation. The MBDA component with the strongest association with change in arterial inflammation was serum amyloid A (SAA). CONCLUSIONS: Among treated RA patients, achieved MBDA predicts of changes in arterial inflammation. Achieving low MBDA at 24 weeks was associated with clinically meaningful reductions in arterial inflammation, regardless of treatment.

The effect of starting metformin on bone mineral density among women with type 2 diabetes in the Study of Women's Health Across the Nation (SWAN).

We examined longitudinal changes in BMD among women in the mid-life starting metformin. Study subjects were 57 years old (mean), and 36% were White. Women initiating metformin were similar to noninitiators. During the 3-year follow-up, BMD loss at all anatomic areas was similar between groups and in subgroups including baseline fasting blood glucose. PURPOSE/INTRODUCTION: Women with type 2 diabetes have higher bone mineral density (BMD), experience slower BMD loss, but have increased fracture risk. Data regarding the effect of metformin on BMD remain discordant. We examined longitudinal changes in BMD among women in the mid-life starting metformin. METHODS: Participants in the Study of Women's Health Across the Nation (SWAN), a diverse community-based US cohort, with BMD measurements were evaluated. Propensity score matching helped balance baseline characteristics of metformin initiators versus noninitiators. Mixed model regression tested the change in BMD between groups. RESULTS: Subjects (n = 248) were 57.4 years old (mean), and 35.9% were White. Women initiating metformin (n = 124) were similar to noninitiators (n = 124) in age and race/ethnicity. During the median 3-year follow-up, BMD loss at all anatomic areas was similar between the metformin initiators and nonusers (all p > 0.3). Subgroup analyses including baseline fasting blood glucose showed no between-group differences. Initiation of metformin (vs. not) in peri-menopausal women was not associated with BMD changes. CONCLUSIONS: Women in the mid-life starting metformin had longitudinal changes in BMD very similar to other women not starting metformin.

Know Thy User: Designing Digital Tools for Rheumatology Patients.

Imagine you are an ambitious technology innovator keen on advancing health care in the digital era. You could have chosen another industry, but you select health care because you want to make a difference in people's lives.

Improving the accuracy of automated gout flare ascertainment using natural language processing of electronic health records and linked Medicare claims data.

BACKGROUND: We aimed to determine whether integrating concepts from the notes from the electronic health record (EHR) data using natural language processing (NLP) could improve the identification of gout flares. METHODS: Using Medicare claims linked with EHR, we selected gout patients who initiated the urate-lowering therapy (ULT). Patients' 12-month baseline period and on-treatment follow-up were segmented into 1-month units. We retrieved EHR notes for months with gout diagnosis codes and processed notes for NLP concepts. We selected a random sample of 500 patients and reviewed each of their notes for the presence of a physician-documented gout flare. Months containing at least 1 note mentioning gout flares were considered months with events. We used 60% of patients to train predictive models with LASSO. We evaluated the models by the area under the curve (AUC) in the validation data and examined positive/negative predictive values (P/NPV). RESULTS: We extracted and labeled 839 months of follow-up (280 with gout flares). The claims-only model selected 20 variables (AUC = 0.69). The NLP concept-only model selected 15 (AUC = 0.69). The combined model selected 32 claims variables and 13 NLP concepts (AUC = 0.73). The claims-only model had a PPV of 0.64 [0.50, 0.77] and an NPV of 0.71 [0.65, 0.76], whereas the combined model had a PPV of 0.76 [0.61, 0.88] and an NPV of 0.71 [0.65, 0.76]. CONCLUSION: Adding NLP concept variables to claims variables resulted in a small improvement in the identification of gout flares. Our data-driven claims-only model and our combined claims/NLP-concept model outperformed existing rule-based claims algorithms reliant on medication use, diagnosis, and procedure codes.

Thoracic Duct Visualization in Esophageal Resection: A Pilot Trial.

INTRODUCTION: Inadvertent thoracic duct injury is common during esophagectomy and may result in postoperative chylothorax. This study's objective was to investigate utility of patent blue injection as a modality for intraoperative thoracic duct visualization. METHODS: A prospective, single-arm, interventional study of patients undergoing minimally invasive esophagectomy was performed. Patients were injected with patent blue dye into both groins prior to thoracic stage of surgery and assessed for duct visualization. Control group was formed by propensity score matching using retrospectively collected data regarding patients who underwent esophagectomy. RESULTS: A total of 25 patients were included in analysis, compared to a control of 50 patients after matching. Thoracic duct was visualized in 60% of patients in the study group (15/25 patients). Significant differences were found between study and control groups (p < 0.05) with regards to median operative time (422 vs. 285 min, respectively), overall complications (16 vs. 34%, respectively), and median postoperative length of stay (13.5 vs. 10 days, respectively). There was a difference in rate of chyle leak between study and control groups; however, this was not significant (0 vs. 12%, respectively, p = 0.17). CONCLUSION: Patent blue injection represents a simple method for thoracic duct visualization during minimally invasive esophagectomy which may improve surgical outcomes.

Editorial Commentary: Patients May Have Posterior Glenoid Labral Tears in the Absence of Instability or Magnetic Resonance Imaging Findings.

Posterior labral tears occur more often than imagined 25 years ago. Although such tears are generally identified in patients with posterior shoulder instability, the spectrum of labral tears in patients without instability creates a challenging diagnosis. Both physical examination and magnetic resonance imaging interpretation are difficult. Pathology encompassing posterior labral tears without instability notably reveals differences compared with throwers with posterior labral tears and patients with posterior instability. Recent research has identified 3 tear types: occult (type 1), incomplete (type 2), and complete (type 3). Attention to diagnosis deserves critical attention, in addition to tailoring of repair techniques to address the appropriate conditions in the shoulder. Even in patients without posterior instability and with ambiguous magnetic resonance imaging or magnetic resonance arthrography findings, posterior shoulder pain during daily activities or sports may indicate a posterior labral tear. Arthroscopic posterior labral repair without capsular plication provides good clinical outcomes and high rates of return to sport and labral healing.

Editorial Commentary: Magnetic Resonance Arthrogram Is More Accurate and Precise Than Conventional Magnetic Resonance Imaging for Evaluating Labral Tears After First-Time Shoulder Dislocation.

Recent research shows that magnetic resonance arthrogram offers better definition of certain shoulder pathology, especially labral tears, compared with magnetic resonance imaging (MRI). Conventional MRI accuracy and precision deteriorate after 2 weeks, and few health delivery environments achieve MRI within 14 days of a shoulder dislocation. Moreover, further loss of MRI accuracy is time dependent. Although magnetic resonance arthrogram should be considered a first-line imaging study when evaluating shoulder instability more than 2 weeks after the patient's injury, one must also consider clinical value and cost-effectiveness.

Editorial Commentary: Bone Marrow Stimulation or Microfracture May Not Enhance the Success of Arthroscopic Rotator Cuff Repair.

Bone Marrow Stimulation (BMS) is intended to provide a very low-cost, local source of marrow elements to improve healing and outcomes following rotator cuff repair. However, meta-analysis does not show that this results in improvement in rotator cuff tear outcomes or healing (as assessed by magnetic resonance imaging or ultrasound). That said, some studies do show lower retear rates with BMS; thus, when faced with challenged biology, this low-cost and low-risk solution may still have merit.

Editorial Commentary: Bio-inductive Collagen Implant to Augment Repair of Rotator Cuff Tears May Be Less Effective for Massive Tears and Revision Repair.

To improve healing after rotator cuff repair, synthetic, allograft, and dermal xenograft patches have been shown to significantly improve strength and load. Recent research has shown that a bio-inductive bovine collagen implant results in improvement in healing in partial-thickness, small, medium, and even large tears, but thus far, repair of massive and revision tears with augmentation is no better than repair alone. Optimizing these challenging repairs remains difficult and elusive.

Editorial Commentary: Patients 75 Years and Older Achieve Rotator Cuff Repair Outcome Similar to Younger Patients with Proper Surgical Indications.

Recent research shows that similar early outcomes can be expected after arthroscopic rotator cuff repair in patients 75 years or older compared to a propensity-matched group under age 75 years. Retear rates are similar. Yet, younger patients show greater range of motion and strength. Proper patient selection is vital; it may be that older patients are indicated for rotator cuff repair surgery with less frequency.

Editorial Commentary: Two-Thirds Glenoid Height Technique Used to Generate a "Perfect Circle" Improves Reliability in Measuring Shoulder Glenoid Bone Loss.

When determining surgical options for shoulder stabilization, patient age, lifestyle, and sport activities help inform which procedure to select. Additionally, there is a need for solidifying the accuracy and effectiveness of measuring glenoid bone loss, which can be the critical factor in choosing a soft tissue or bony augmentation procedure. Makovicka et al. found that using two-thirds of the glenoid height to generate a perfect-circle, rather than a "best-fit" circle improved reliability of MRI-based bone loss measurement. Two-thirds height technique employs a more objective measure of glenoid height, producing a perfect circle used to subsequently estimate glenoid bone loss, which is consistently reproducible, and can be performed in most clinical settings. This was supported by the improved intra-class correlation coefficient from the two-thirds height perfect circle over the "best-fit" circle measurement observed in this study.