Low back pain as an occupational risk among supermarket cashiers in KwaZulu-Natal, South Africa

Background: Work-related low back pain (LBP) has received growing attention, especially regarding the effect it has on work productivity and activities of daily living (ADL). Supermarket cashiers are at high risk of LBP due to maintaining awkward postures for prolonged periods. Objectives: To investigate the prevalence and intensity of LBP among supermarket cashiers in KwaZulu-Natal, South Africa, and to identify occupational and non-occupational risk factors for LBP. Methods: Supermarket cashiers from 12 conveniently selected stores of a major South African supermarket franchise were included in this cross-sectional study. Questionnaires were administered in October and November 2018. Mean LBP disability scores were used as a measure of pain intensity experienced during various activities. Univariate analysis of variance (ANOVA) was used to measure the effect size of different variables on the LBP intensity score. The associations between LBP and both occupational and non-occupational factors were assessed using Fischer's exact test and forward stepwise logistic regression analysis. Results: One hundred and forty-six cashiers participated in the study. Most of the participants reported having minimal LBP (n = 132, 90.4%), indicating that they could cope with most living activities. Based on the mean disability scores, only the effect size of age was large. The odds of having LBP were associated with age 30 years and older (p = 0.001), race other than black African (p = 0.037), and working for more than 10 hours a day (p = 0.039). Conclusion: Reporting of LBP was common among the supermarket cashiers in this study. Older workers are at a higher risk of having LBP, which may be exacerbated by long working hours. Workplace interventions such as ergonomic programmes, structured and defined working hours, and home-based interventions such as exercise therapy, should be implemented.

Alterations in Intracardiac Flow Patterns Affect Mitral Leaflets Dynamics in a Model of Ischemic Mitral Regurgitation.

PURPOSE: This study was to evaluate the effects of ischemic mitral regurgitation (IMR) on vortex formation and leaflet dynamics using an established porcine infarct model of IMR. METHODS: Using direct coronary ligation, five animals were subjected to a posterolateral myocardial infarction (MI) followed by an MRI at 12-weeks post MI. MR imaging consisted of 4D time-resolved left ventricular (LV) flow, full coverage 2D LV cine, and high resolution 2D cine of mitral valve dynamics. Five additional naïve animals underwent identical imaging protocols to serve as controls. Image analysis was performed to obtain mitral transvalvular flows as well as LV volumes throughout the cardiac cycle. In addition, anterior to posterior mid-leaflet tip distances were measured throughout the cardiac cycle for determination of temporal leaflet dynamics. RESULTS: It was found IMR caused asymmetric vortex ring formation with the anterior vortex having a lower vorticity relative to its posterior counterpart. In contrast, normal ventricles create symmetric and tightly curled vortices in the basal chamber just underneath the mitral leaflets which conserve kinetic energy and aid in effective ejection. IMR animals were also evaluated for leaflet separation and were found to have a greater leaflet opening and achieved peak vorticity and peak leaflet opening later than control animals. CONCLUSION: In conclusion, this study shows the effects that altered vortex formation, due to IMR, can have on ventricular filling and leaflet dynamics. These findings have important implications for understanding blood flow through the dilated heart and how ring annuloplasty and volume reduction interventions may influence mitral valve dynamics.

Assessment of synchronized direct mechanical ventricular actuation in a canine model of left ventricular dysfunction.

Direct mechanical ventricular actuation (DMVA) is an experimental procedure that provides biventricular cardiac assistance by intracorporeal pneumatic compression of the heart. The advantages this technique has over other assist devices are biventricular assistance, no direct blood contact, pulsatile blood flow, and rapid, less complicated application. Prior studies of nonsynchronized DMVA support have demonstrated that a subject can be maintained for up to 7 days. The purpose of this study was to determine the acute hemodynamic effects of cardiac synchronized, partial DMVA support in a canine model (RVP) of left ventricular (LV) dysfunction. The study consisted of rapidly pacing seven dogs for 4 weeks to create LV dysfunction. At the conclusion of the pacing period, the DMVA device was positioned around the heart by means of a median sternotomy. The animals were then imaged in a 1.5 T whole body high speed clinical MR system, with simultaneous LV pressure recording. Left ventricular pressure-volume (PV) loops of the nonassisted and DMVA assisted heart were generated and demonstrated that DMVA assist shifted the loops leftward. In addition, assist significantly improved pressure dependent LV systolic parameters (left ventricular peak pressure and dp/dt max, p < 0.05), with no diastolic impairment. This study demonstrates that DMVA can provide synchronized partial assist, resulting in a decrease in the workload of the native heart, thus having a potential application for heart failure patients.

Dynamic cardiomyoplasty decreases myocardial workload as assessed by tissue tagged MRI.

The effects of dynamic cardiomyoplasty (CMP) on global and regional left ventricular (LV) function in end-stage heart failure still remain unclear. MRI with tissue-tagging is a novel tool for studying intramyocardial motion and mechanics. To date, no studies have attempted to use MRI to simultaneously study global and regional cardiac function in a model of CMP. In this study, we used MRI with tissue-tagging and a custom designed MR compatible muscle stimulating/pressure monitoring system to assess long axis regional strain and displacement variations, as well as changes in global LV function in a model of dynamic cardiomyoplasty. Three dogs underwent rapid ventricular pacing (RVP; 215 BPM) for 10 weeks; after 4 weeks of RVP, a left posterior CMP was performed. After 1 year of dynamic muscle stimulation, the dogs were imaged in a 1.5 T clinical MR scanner. Unstimulated and muscle stimulated tagged long axis images were acquired. Quantitative 2-D regional image analysis was performed by dividing the hearts into three regions: apical, septal, and lateral. Maximum and minimum principal strains (lambda, and lambda2) and displacement (D) were determined and pooled for each region. MR LV pressure-volume (PV) loops were also generated. Muscle stimulation produced a leftward shift of the PV loops in two of the three dogs, and an increase in the peak LV pressure, while stroke volume remained unchanged. With stimulation, lambda1 decreased significantly (p<0.05) in the lateral region, whereas lambda2 increased significantly (p<0.05) in both the lateral and apical regions, indicating a decrease in strain resulting from stimulation. D only increased significantly (p<0.05) in the apical region. The decrease in strain between unassisted and assisted states indicates the heart is performing less work, while maintaining stroke volume and increasing peak LV pressure. These findings demonstrate that the muscle wrap functions as an active assist, decreasing the workload of the heart, while preserving total pump performance.

Pilot study for appropriate anti-infective community therapy. Effect of a guideline-based strategy to optimize use of antibiotics.

OBJECTIVE: To determine whether a community-wide, multi-intervention educational strategy (CoMPLI model) could enhance adoption of clinical guidelines and improve the use of antibiotics. DESIGN: Before-after trial using baseline and study periods with a control group. SETTING: A small community in central Ontario. PARTICIPANTS: Health professionals, the general public, and the pharmaceutical industry. INTERVENTIONS: The educational strategy (CoMPLI), carried out during 6 winter months, consisted of continuing medical education sessions for health professionals and pharmaceutical representatives and a parallel public education campaign that included town hall meetings and pamphlets distributed by local pharmacists. The two main messages were: do not use antibiotics for viral respiratory infections, and use drugs recommended in the publication, Anti-infective Guidelines for Community-Acquired Infections. MAIN OUTCOME MEASURES: Total number of antibiotic claims and adjusted odds ratios (OR) were used to measure the likelihood of physicians prescribing first- or second-line agents compared with the previous year and compared with control physicians. RESULTS: Claims in the study community decreased by nearly 10% during the 6-month study period compared with the baseline period from the previous year. Study physicians were 29% less likely (OR-1 = 0.71, range 0.67 to 0.76) to prescribe second-line antibiotics during the study period than physicians in the rest of the province. CONCLUSIONS: Physicians participating in the pilot study were more likely to follow drug recommendations outlined in published guidelines.

Ten weeks of rapid ventricular pacing creates a long-term model of left ventricular dysfunction.

OBJECTIVE: Rapid ventricular pacing produces a reliable model of heart failure. Cessation after 4 weeks of rapid ventricular pacing results in rapid normalization of left ventricular function, but the left ventricle remains persistently dilated. We present novel data that show that prolonged rapid ventricular pacing (10 weeks) creates a model of chronic left ventricular dysfunction. METHODS: In 9 dogs undergoing 10 weeks of rapid ventricular pacing, left ventricular function and volumes were serially assessed by using 2-dimensional echocardiography and pressure-volume analysis for 12 weeks after cessation of pacing. RESULTS: Increased end-diastolic volume and decreased systolic and diastolic function were seen at the end of pacing. By 2 weeks of recovery from rapid ventricular pacing, end-diastolic volume and ejection fraction were partially recovered but did not improve further thereafter. Load-independent and load-sensitive indices of function obtained by pressure-volume analysis at 8 and 12 weeks of recovery confirmed a persistence of both systolic and diastolic dysfunction. In addition, left ventricular mass increased with pacing and remained elevated at 8 and 12 weeks of recovery. Four of these dogs studied at 6 months of recovery showed similar left ventricular abnormalities. CONCLUSION: Ten weeks of rapid ventricular pacing creates a long-term model of left ventricular dysfunction.

Cardiac-respiratory gating method for magnetic resonance imaging of the heart.

In studies of transmural myocardial function, acquisitions of high spatial and temporal resolution tagged cardiac images often exceed the practical time limit for breath-hold fast imaging techniques. Therefore, a dual cardiac-respiratory gating device has been constructed to acquire SPAMM-tagged cardiac MR images at or near end-expiration during spontaneous breathing, by providing an external trigger to a conventional MRI system. Combined cardiac and respiratory gating essentially eliminates the respiratory motion artifacts in tagged cardiac MR images. Compared to cardiac-gated images obtained during intermittent breath-holds, cardiac-respiratory gated images show improved tag-myocardium contrast due to magnetization recovery during inspiration.

Long-term dynamic cardiomyoplasty improves chronic and acute myocardial energetics in a model of left ventricular dysfunction.

BACKGROUND: We present the first long-term evaluation of myocardial energetics after dynamic cardiomyoplasty (CMP) in a model of left ventricular (LV) dysfunction. METHODS AND RESULTS: Seventeen dogs underwent rapid ventricular pacing (RVP) to create heart failure. Eight dogs were randomly selected to undergo cardiomyoplasty. All dogs continued RVP for 6 additional weeks, whereas the CMP dogs underwent a simultaneously delivered synchronized muscle wrap conditioning protocol. After termination of RVP at 10 weeks in all dogs, myoplasty dogs continued to receive muscle wrap stimulation until the terminal study. Pressure-volume analysis to assess LV energetics was conducted at baseline and 4 weeks and 3 months after termination of RVP (6 months after baseline). At 6 months, CMP dogs displayed enhanced contractility, lower volumes, and more optimal energetics compared with control animals. Acute muscle wrap stimulation further increased effective contractility and myocardial efficiency compared with unassisted beats. CONCLUSIONS: The decrease in NYHA functional class that occurs in patients after dynamic cardiomyoplasty may be secondary to its beneficial effects on long-term myocardial function, volume, and energetics.

Noninvasive measurement of the human brachial artery pressure-area relation in collapse and hypertension.

A noninvasive method to obtain pressure-lumen area (P-A) measurements of the human brachial artery is introduced. The data obtained from this method are analyzed using a mathematical model of the relationship between vessel pressure and lumen area including vessel collapse and hypertension. An occlusive arm cuff is applied to the brachial artery of ten normal subjects. The cuff compliance is determined continuously by means of a known external volume calibration pump. This permits the computation of the P-A curve of the brachial artery under the cuff. A model is applied to analyze the P-A relation of each subject. The results show that the lumen area varies considerably between subjects. The in vivo resting P-A curve of the brachial artery possesses features similar to that of in vitro measurements. A primary difference is that the buckling pressure is higher in vivo, presumably due to axial tension, as opposed to in vitro where it is near zero or negative. It is found that hypertension causes a shift in the P-A curve towards larger lumen areas. Also, the compliance-pressure curve is shown to shift towards higher transmural pressures. Increased lumen area provides an adaptive mechanism by which compliance can be maintained constant in the face of elevated blood pressure, in spite of diminished distensibility.

Modified rapid ventricular pacing: a chronic model of heart failure for evaluation of new surgical therapies.

Rapid ventricular pacing (RVP) in dogs creates a well characterized model of dilated cardiomyopathy. Standard pacing protocols use RVP at 240-260 beats/min for 2-4 weeks, and result in high mortality rates if continued longer. The authors describe a modification of RVP that results in significant heart failure by 4 weeks, but can be continued for up to 10 weeks with low mortality. Nineteen mongrels underwent RVP at 215 beats/min for 10 weeks. Serial pressure-volume analysis and echocardiography were performed in this model to assess longitudinally changes in left ventricular (LV) function and volumes. The mortality rate was 10%. Significant progressive LV dysfunction with concomitant LV enlargement was observed throughout the pacing period. Finally, norepinephrine levels were elevated at the end of pacing, consistent with an activated sympathetic system. This modified RVP protocol permits long-term pacing with a low mortality rate and results in progressive heart failure throughout the pacing period. This model would be useful in the long-term evaluation of newer surgical and medical therapies of the failing heart.

Determination of global function and regional mechanics of dynamic cardiomyoplasty using magnetic resonance imaging.

This study used tissue tagged magnetic resonance (MR) to assess regional strain and generate pressure-volume (PV) loops in a canine model of cardiomyoplasty (CMP). Three dogs with rapid ventricular pacing induced heart failure underwent dynamic CMP chronic cardiac assistance for 1 year. At the end of the study period, we performed a MR study with the myostimulator "on" and "off" and recording of left ventricular (LV) pressure. We determined the short axis displacement (D) and maximal and minimal principal strains (lambda1 and lambda2) by quantitative two-dimensional regional spatial modulation of magnetization visualization utility image analysis. LV PV loops were generated by combining the LV volume data from the MR images with the LV pressure recorded during imaging. Muscle stimulation produced a leftward shift of the LV PV loops in two of the three dogs, and an increase in LV peak pressure and dp/dt max. In contrast, short axis lambda1 and lambda2 did not change significantly (p = NS). D increased significantly in the anterolateral, posterolateral, and posteroseptal regions (p < 0.05) but did not change for the septal region (p = NS). Flap stimulation augments LV function in the absence of short axis strain change; this suggests that dynamic CMP exerts its main action along the long axis of the heart.

Stabilization of chronic remodeling by asynchronous cardiomyoplasty in dilated cardiomyopathy: effects of a conditioned muscle wrap.

BACKGROUND: Dynamic cardiomyoplasty is a promising new therapy for dilated cardiomyopathy. The girdling effects of a conditioned muscle wrap alone have recently been postulated to partly explain its mechanism. We investigated this effect in a canine model of chronic dilated cardiomyopathy. METHODS AND RESULTS: Twenty dogs underwent rapid ventricular pacing (RVP) for 4 weeks to create a model of dilated cardiomyopathy. Seven dogs were then randomly selected to undergo subsequent cardiomyoplasty, and all dogs had 6 weeks of additional RVP. The cardiomyoplasty group also received 6 weeks of concurrent skeletal muscle stimulation consisting of single twitches delivered asynchronously at 2 Hz to transform the wrap without active assistance. All dogs were studied by pressure-volume analysis and echocardiography at baseline and after 4 and 10 weeks of pacing. Systolic indices, including ejection fraction (EF), end-systolic elastance (Ees), and preload-recruitable stroke work (PRSW) were all increased at 10 weeks in the wrap versus controls (EF, 34.0 versus 27.1, P=.008; Ees, 1.65 versus 1.26, P=.09; PRSW, 35.9 versus 25.5, P=.001). Ventricular volumes, diastolic relaxation, and left ventricular end-diastolic pressures stabilized in the cardiomyoplasty group but continued to deteriorate in controls. Both the end-systolic and end-diastolic pressure-volume relationships shifted farther rightward in controls but remained stable in the cardiomyoplasty group. CONCLUSIONS: In addition to potential benefits from active systolic assistance, benefits from dynamic cardiomyoplasty appear to be partially accounted for by the presence of a conditioned muscle wrap alone. This conditioned wrap stabilizes the remodeling process of heart failure, arresting progressive deterioration of systolic and diastolic function.

Dynamic cardiomyoplasty: its chronic and acute effects on the failing heart.

OBJECTIVES: Dynamic cardiomyoplasty is an alternative therapy for end-stage heart failure. We investigated the mechanisms, both acute and chronic, by which a synchronously stimulated conditioned muscle wrap affects left ventricular function in a chronic canine model of dilated cardiomyopathy. METHODS: Nineteen dogs underwent rapid ventricular pacing at a rate of 215 beats/min for 4 weeks to create a model of heart failure. Eight dogs were then randomly selected to undergo cardiomyoplasty, and all dogs received 6 additional weeks of rapid ventricular pacing. The cardiomyoplasty group also received a graded muscle conditioning protocol of synchronized burst stimulation to transform the muscle wrap. All dogs were studied with pressure-volume analysis and echocardiography at baseline and after 4 and 10 weeks of rapid ventricular pacing. Data in the cardiomyoplasty group were analyzed with the stimulator off, with it augmenting every beat (1:1), and with it augmenting only every other beat (1:2). RESULTS: Stimulator "of" data at 10 weeks of rapid pacing demonstrated chronic effects by enhanced ventricular function (end-systolic elastance = 1.80 after myoplasty vs 1.17 for controls, p = 0.005) and a stabilization of volumes and composite end-systolic and end-diastolic pressure-volume relations in the cardiomyoplasty group when compared with controls. Myoplasty stimulation increased apparent contractility (preload recruitable stroke work = 31.3 for stimulator "of" vs 40.6 for stimulator 1:2 assisted beats [p < 0.05] and vs 45.4 for stimulator 1:1 [p < 0.05]). CONCLUSIONS: Benefits from dynamic cardiomyoplasty are by at least two mechanisms: (1) the girdling effects of a conditioned muscle wrap, which halts the chronic remodeling of heart failure, and (2) active systolic assistance, which augments the apparent contractility of the failing heart.

Accuracy of ICD-9-CM codes in hospital morbidity data, Victoria: implications for public health research.

Hospital morbidity data in the form of International classification of diseases, 9th revision, clinical modification codes are often used for epidemiological studies and disease surveillance. We aimed to evaluate the reliability of the Victorian In-patient Minimum Database for use in epidemiological studies and disease surveillance. Data from 1993-94 were collected, as part of a coding audit of public hospitals in Victoria, from 7052 randomly selected records. The frequency of discrepancy in any coding field was 53 per cent, and of discrepancy in the principal diagnosis, 22 per cent. New Australian national diagnosis-related group (ANDRG) codes were assigned as a result of discrepancy in 13.6 per cent of cases. Discrepancy rates increased with increasing rarity of ANDRG, from 50 per cent to 56 per cent. Predictors of change in ANDRG assignment were discrepancy in the principal diagnosis, ANDRG frequency of over 0.6 per cent, more than three diagnoses, medical ANDRGs, length of stay over five days and rural hospitals. Rates of any discrepancy increased from 36 per cent in patients with one diagnosis to 94 per cent in patients with 12 diagnoses. The discrepancy rates were consistent with those of other studies. Coding discrepancy is likely to be caused by universal difficulties associated with the coding of hospital records, rather than any unique local problems. The predictors of discrepancy suggest that more complex cases are more prone to coding discrepancy. In areas where the database is less reliable, use of a supplementary data source, such as link-age studies, would improve reliability.

A casemix for mental health services: the development of the mental health and substance abuse components of the Australian national diagnosis-related groups.

OBJECTIVE: To describe the development of the mental health and substance abuse sections of the version of the Australian casemix system, Australian national diagnosis-related groups 3 (AN-DRG 3), released in July 1995. METHOD: The guiding principles and data sources used to construct the mental health and substance abuse components of AN-DRG 3 are described by the group who undertook that task. The group used data sets of patients separating from hospitals throughout Australia, and from hospitals in South Australia, to examine the capacity of existing and revised diagnosis-related groups (DRGs) to predict patients' lengths of hospital stay. They also reviewed the lists of conditions allowed as complicating and comorbid conditions within the AN-DRG system. RESULTS: A variety of recommendations were made including: moving organic mental disorder DRGs to a neuroscience area of the AN-DRG; completely reorganising the mental health section of the casemix; creating a number of narrowly defined DRGs covering areas such as schizophrenia, major affective disorders, anxiety disorders and eating disorders, while allowing for a limited number of more heterogenous DRGs and simplifying substance abuse DRGs into groups covering alcohol and other substances, and differentiating intoxication and withdrawal from abuse and dependency. CONCLUSIONS: A casemix dialect based on clinical diagnosis, which describes mental health and substance abuse problems in terms which should be familiar to clinicians, has been developed. Its applications and limitations are briefly discussed.

Development of AN-DRGs: meeting the concerns of clinicians.

The diagnosis-related group (DRG) classification has been the centre of Commonwealth and various State initiatives to modify significantly the basis for funding of public hospitals in Australia. The classification has been extensively criticised by Australian clinicians as being out of date and inappropriate for several areas of medicine. Developments in Australia to improve the DRGs classification have led to the Australian national version, AN-DRGs. The differentiating features of AN-DRGs are summarised and priority areas for further development are suggested. Further substantial improvement in the classification can be obtained only if new approaches to classification design are considered and if it is supplemented by measures of severity of illness.

Adapting DRGs: the British, Canadian and Australian experiences.

The DRG classification was developed in the United States, and has been widely used there for analytical and resource allocation purposes. Its utility has been recognised in other countries. Some have adopted US versions without change, and others have chosen to develop their own adaptations. This paper discusses the processes and outcomes of adaptation in Canada, Britain and Australia. An attempt is made to generalise the trends. It is concluded that there is a high degree of similarity of intent, although different solutions have been adopted in some cases. Where major differences remain, they are mostly a consequence of the lack of resources to pursue all opportunities for refinement at the same time. All three countries have correctly focused on involvement of their own clinician groups. However, they have tended to restrict their view to US experiences when looking overseas. It is argued that greater attention should be paid to sharing their ideas with countries with which they have a greater degree of similarity.

Where are DRGs going?

The diagnosis related groups (DRG) classification of acute inpatient episodes was developed in the United States to meet the perceived needs of the U.S. hospital sector. Thus far, it has been used in Australia without significant modification. In this paper, we assess the DRG system in terms of basic principles of classification design and suggest some possible revisions which might be considered if there were reason to contemplate major changes for Australia. We conclude by making some suggestions on the process of managing the development of DRGs in Australia.