Norma Coffey

Functional Data Analysis of Running Kinematics in Chronic Achilles Tendon Injury

PURPOSE Chronic Achilles tendon (AT) injuries are common, but kinematic studies confirming the exact mechanisms of injury and how orthoses are effective are lacking. Existing analysis often relies on discrete measures and provides an incomplete analysis because many of the data are discarded. Functional data analysis (FDA) views the entire dataset as a function, thus retaining the main features of the curve. This study uses FDA to examine the mechanisms of chronic AT injury and the functional effects of orthoses. METHODS Twelve subjects with a history of chronic AT injury and 12 controls ran on a treadmill with and without customized orthoses. Three-dimensional kinematic data were obtained using Qualisys motion capture systems operating at 200 Hz. Ankle dorsiflexion (ADF), knee flexion (KF), eversion (EV), calcaneal, and leg abduction angles were calculated across stance. These angle data were represented as functions, and functional principal components were extracted to describe the factors accounting for variation in the data. These components were compared in AT versus control groups and orthoses versus no-orthoses conditions. RESULTS Kinematic differences were observed, with the AT group showing greater EV, ADF, and KF during stance, whereas orthoses reduced ADF but increased EV. Different patterns of frontal plane variation distinguished between groups and conditions. CONCLUSION Results provided additional information about movement patterns compared to traditional approaches and identified the first half of stance as the most relevant period in injury occurrence. The study showed evidence that variability is related to the presence of injury in this clinical population. Further FDA focusing on within-subject variation is recommended to gain greater insight into the role of variability in injury occurrence.

Common functional principal components analysis: A new approach to analyzing human movement data

In many human movement studies angle-time series data on several groups of individuals are measured. Current methods to compare groups include comparisons of the mean value in each group or use multivariate techniques such as principal components analysis and perform tests on the principal component scores. Such methods have been useful, though discard a large amount of information. Functional data analysis (FDA) is an emerging statistical analysis technique in human movement research which treats the angle-time series data as a function rather than a series of discrete measurements. This approach retains all of the information in the data. Functional principal components analysis (FPCA) is an extension of multivariate principal components analysis which examines the variability of a sample of curves and has been used to examine differences in movement patterns of several groups of individuals. Currently the functional principal components (FPCs) for each group are either determined separately (yielding components that are group-specific), or by combining the data for all groups and determining the FPCs of the combined data (yielding components that summarize the entire data set). The group-specific FPCs contain both within and between group variation and issues arise when comparing FPCs across groups when the order of the FPCs alter in each group. The FPCs of the combined data may not adequately describe all groups of individuals and comparisons between groups typically use t-tests of the mean FPC scores in each group. When these differences are statistically non-significant it can be difficult to determine how a particular intervention is affecting movement patterns or how injured subjects differ from controls. In this paper we aim to perform FPCA in a manner allowing sensible comparisons between groups of curves. A statistical technique called common functional principal components analysis (CFPCA) is implemented. CFPCA identifies the common sources of variation evident across groups but allows the order of each component to change for a particular group. This allows for the direct comparison of components across groups. We use our method to analyze a biomechanical data set examining the mechanisms of chronic Achilles tendon injury and the functional effects of orthoses.

Group follow-up compared to individual clinic visits after structured education for type 1 diabetes: A cluster randomised controlled trial☆

AIM To compare the effectiveness of group follow-up with individual follow-up after participation in the Dose Adjustment for Normal Eating (DAFNE) structured education programme. METHODS Cluster randomised controlled trial involving 437 adults with type 1 diabetes attending hospital diabetes clinics in Ireland. All participants received DAFNE at baseline. Intervention arm participants received 2 group education sessions post-DAFNE and did not attend clinics. Control arm participants received 2 one-to-one clinic visits post-DAFNE. RESULTS We observed no significant difference in the primary outcome (change in HbA1c) at 18 months follow-up (mean difference 0.14%; 95% CI -0.33 to 0.61; p=0.47). Secondary outcomes, including rates of severe hypoglycaemia, anxiety, depression, the burden of living with diabetes and quality of life did not differ between groups. Mean level of HbA1c for the entire sample (regardless of treatment arm) did not change between baseline and 18 month follow-up (p=0.09), but rates of severe hypoglycaemia, diabetes related hospital attendance, levels of anxiety, depression, the burden of living with diabetes, quality of life and treatment satisfaction all significantly improved. CONCLUSIONS Our data suggest that group follow-up as the sole means of follow-up after structured education for individuals with type 1 diabetes is as effective as a return to one-to-one clinic visits.

Predictors of quality of life gains among people with type 1 diabetes participating in the Dose Adjustment for Normal Eating (DAFNE) structured education programme.

AIMS To examine predictors of quality of life gains among people with type 1 diabetes following the Dose Adjustment for Normal Eating (DAFNE) self-management training programme. METHODS Clinical and questionnaire data were collected from 437 patients from 6 hospital centres before, and 18 months post-DAFNE intervention. Glycated haemoglobin (HbA(1c)), weight, height, and blood pressure levels were recorded by clinicians during clinic appointments. Questionnaires included the Diabetes-Specific Quality of Life Scale (DSQOLS), the Problem Areas in Diabetes Scale (PAID) and the Hospital Anxiety and Depression Scale (HADS). Basic demographics were recorded at baseline. Linear mixed models were fitted to identify predictors of change in quality of life at an 18 month follow-up assessment. RESULTS Patients with high levels of diabetes-related distress experienced greatest improvement in DSQOLS quality of life scores (p = 0.001). Patients with poor glycaemic control (higher levels of HbA(1c); p = 0.03) and those with high levels of anxiety (p = 0.001) experienced the greatest reductions in diabetes-related distress. CONCLUSIONS Patients with higher baseline levels of anxiety, higher levels of diabetes-related distress and higher baseline levels of HbA(1c) are most likely to experience quality of life gain from participation in self-management programmes such as DAFNE.

A prospective observational study of techniques to remove corneal foreign body in the emergency department

Introduction Patients with corneal foreign bodies (CFBs) often present to the emergency department (ED). However, removal techniques vary among emergency physicians (EPs). A prospective, single-blinded, observational study was performed to compare slit-lamp-aided (SLA) versus non-slit-lamp-aided (NSLA) CFB removal by EPs. Methods Five EPs enrolled consecutive patients with a CFB over 3 months. One blinded EP reviewed patients after 3 days. The study end points were: change in visual acuity; visual analogue pain scale (VAS) score at 12 and 24 h; satisfaction rating; symptoms at follow-up; and rate of complications. Results 54 patients were enrolled: 28 had SLA removal and 26 NSLA removal; 52 were male; 22 had undergone previous CFB removal; six were wearing eye protection at the time of injury. Forty-three patients were reviewed: 26 by attendance and 18 by telephone. There was no difference in any end points at review. However, patients in the SLA group had median VAS scores that were 1.5 cm lower after 24 h than patients in the NSLA group (p=0.43, 95% CI −2.0 to 1.0). One patient in the SLA group developed keratitis. Conclusions We show that patient satisfaction ratings, complications and visual acuity were similar for the two methods. There was a trend for increased pain in the NSLA group at 12 and 24 h. Slit-lamp biomicroscopy and the use of magnification to remove CFBs remains the gold standard of care, and more intensive training should be given to EPs at the departmental level, particularly in EDs that receive patients with eye injuries.

O-81 The impact of caseload on practice patterns in breast cancer: Evidence from the UK Breast Screening Programme

Studies examining the relationship between caseload and surgical practice in breast cancer have generally involved a small number of units or patients, and have been based on outdated practice patterns. We aimed to examine the caseload volume of screening units and individual breast cancer surgeons, and to investigate the relationship between these volumes and practice patterns in the contemporary setting. The non-operative and operative history of screen-detected breast cancers, diagnosed in women who were screened between 2000 and 2008 within the UK Breast Screening Programme, was extracted from national databases. This information was then correlated with unitand individual surgeon caseload. There were 14,008,192 screening events and 110,912 cancers detected over the study period. No differences were seen between practice patterns in the lowversus high-volume units. The percentage of surgeons seeing P30 cases of breast cancer per year rose from 35.4% to 51.6%, whilst the number of surgeons responsible for <10 cases annually decreased from 32.9% to 23.5%, over the study period. There was a positive correlation between the number of cancers seen by individual surgeons and the rate at which they employed SNB (p < 0.001), and performed immediate breast reconstruction (p < 0.001).The number of mastectomies performed was approximately 4% lower in surgeons with high caseload versus those with a low caseload (p = 0.035). Whilst many surgeons are still practicing out-with ABS at BASO guidelines, significant improvements have been made. The important variable in terms of practice patterns is the number of cancers each individual surgeon deals with; the caseload of individual units is less important.