Unusual cardiac injury following blunt chest trauma

Cardiac injury following blunt chest trauma is known to occur, but traumatic rupture of ventricular septum is a rare injury, especially following blunt chest trauma. A case of a 20-year-old male is presented who fell on his back from a 9th-floor window and was resuscitated for 3 hours to no avail. Post-mortem examination confirmed a fracture of the pelvis, pulmonary contusion and rupture of ventricular septum of the heart.

No evidence for multiple-drug prophylaxis for tuberculosis compared with isoniazid alone in Southeast Asian refugees and migrants: completion and compliance are major determinants of effectiveness

BACKGROUND

The use of multiple-drug prophylaxis for tuberculosis (TB) has not been shown to be more effective than prophylaxis with isoniazid alone. The boundary between inactive pulmonary TB (class 4 TB) and culture-negative "active" pulmonary TB (class 3 TB) is often unclear, as is the intention to treat such patients as a preventive measure or as a curative measure.

METHODS

We compared the effectiveness of single drug preventive therapy with isoniazid to the effectiveness of multiple drug preventive therapy for patients with asymptomatic, inactive TB, in a retrospective cohort study of 984 Southeast (SE) Asian migrants and refugees who received prophylaxis between 1978 and 1980.

RESULTS

The rate of TB developing in this cohort was 122 per 100,000 person-years. There was no significant difference in development of TB between people who received isoniazid only and those who received multiple drugs. The only significant predictor of TB was noncompletion of prophylaxis [relative risk (RR) = 62, 95% confidence interval (CI) = 20-194]. Subgroup analysis on people who had completed therapy showed noncompliance as a significant predictor of TB (RR = 16, 95% CI = 1.4-179). The risk of noncompletion (RR = 4.7, 95% CI = 2.37-9.39, P < 0.0001) and noncompliance (RR = 2.2, 95% CI = 1.03-4.7, P = 0.03) was higher for patients who received multiple drugs compared with isoniazid alone. Multiple-drug therapy cost 30 times more than isoniazid alone.

CONCLUSIONS

We did not find evidence in support of the empirical practice of giving multiple drugs for prevention of TB. This practice is also more costly and more likely to result in noncompliance and adverse drug reactions.

In-hospital mortality after transurethral resection of the prostate in Victorian public hospitals

BACKGROUND

The purpose of the present paper was (i) to identify trends in in-hospital mortality after transurethral resection of the prostate (TURP) in Victorian public hospitals; and (ii) to explore associations between in-hospital mortality after TURP and age, adverse events, type of admission (emergency/planned), location of the hospital (metropolitan/rural), teaching status of the hospital and length of stay.

METHODS

Trends in in-hospital mortality after TURP and the associations between in-hospital mortality and the aforementioned variables were studied using International Classification of Diseases, 9th revision, Clinical Modification (ICD-9-CM) coded Victorian hospital morbidity data from public hospitals between 1987-88 and 1994-95. Crude and adjusted odds ratios (OR) and 95% confidence intervals (CI) were based on univariate and multivariate logistic regression, respectively.

RESULTS

After adjustment for age, comorbidity, and other confounding variables, the trend in mortality reduction over time was highly significant (P for trend < 0.0001, 95% CI for trend: 0.84-0.95). Highly significant associations with mortality were observed for emergency admissions (OR = 1.99, P < 0.0001), presence of adverse events (OR = 2.69, P < 0.0001), length of hospital stay (P for trend < 0.0001, 95% for trend: 1.88-2.15) and age (P for trend < 0.0001; 95% CI for trend: 1.26-1.48).

CONCLUSIONS

Routinely collected data from hospitals can provide tentative evidence of improved effectiveness of a surgical treatment, provided analysis takes careful account of potential sources of bias, especially those related to possible changes in case selection over time. These kinds of data should stimulate a joint effort between clinicians, quality assurance experts and epidemiologists to confirm this attribution, and to locate the causative factors.

Preventable Hospitalisations for Diabetic Complications in Rural and Urban Victoria

The objective of the study was to describe and explain variations in rates of hospital admissions for long-term complications of diabetes mellitus in rural and urban Victoria as an indicator of the adequacy of ambulatory care services. The Victorian Inpatient Minimum Database (VIMD), Health Insurance Commission data for 1998, Medical Labour Force Annual Survey 1998, Socioeconomic Indexes for Areas 1996 (SEIFA) and Accessibility/Remoteness Index of Australia (ARIA) were merged to determine the extent to which hospitalisation for complications of diabetes can be predicted from accessibility and utilisation of general practitioner services. The rural and urban differentials for long-term diabetic complications and their strong relationship with GP services, the degree of remoteness, lack of insurance, and Aboriginality reflect issues related to equity and access, patient and GP education, and inclination to seek care, all of which have implications for planning of primary health services in rural areas. This study describes a model for the analysis of ambulatory care sensitive conditions, and illustrates the important use of routine databases combined with other sources of information in quantifying the impact of factors related to primary care services.

In-hospital mortality and associated complications after bowel surgery in Victorian public hospitals

BACKGROUND

The purpose of the present paper was to determine the mortality rate and associated complications after large bowel resection and anastomosis in Victorian public hospitals.

METHODS

A retrospective analysis of data from the Victorian Inpatient Minimum Database (VIMD) was undertaken. The data were collected from all Victorian public hospitals performing hemicolectomy and anterior resection (resection of the rectum with anastomosis) from 1987/88 to 1995/96.

RESULTS

A total of 11036 patients underwent hemicolectomy or anterior resection in the time period studied, there being a 7% increase in the rate of operations performed over the 9 years. Two-thirds of these operations were for carcinoma of the large bowel. The anastomotic leak rate of 4.5% fell slightly but the in-hospital mortality rate of 6.5% did not change over the study period. The total morbidity recorded (mainly major complications) was 24.6%. The patients most at risk of death were the elderly with pre-existing cardiac or respiratory disease undergoing an emergency operation.

CONCLUSIONS

Notwithstanding some inaccuracies of coding and reporting, the morbidity and mortality for surgery of the large intestine remains high, largely due to the comorbidities of the patients, although certain technical complications such as leakage of an anastomosis after anterior resection are still associated with a significantly increased risk of death. Consideration should be given to the routine use of high-dependency nursing units for these high-risk patients after major colorectal surgery, and support from physicians to reduce morbidity and mortality from associated medical conditions worsened by surgery.

Gastric cancer in Tasmania (1978-1992)

A detailed analyses of gastric cancer incidence and mortality rates in Tasmania was done using fifteen years (1978-1992) of population based Tasmanian Cancer Registry data. The age standardised incidence rates for the period were 12.5 per 100,000 men (95% CI 11.4-13.6) and 5.2 per 100,000 women (95% CI 4.6-5.8). The age standardised mortality rates were 10.6 per 100,000 men (95% CI 9.6-11.6) and 4.1 per 100,000 women (95% CI 3.5-4.6). Male:Female ratio of mortality rates was 2.6. Gastric cancer mortality rates have now significantly declined among males (p = .03) and females (p = .02). No significant decline was observed for incidence rates among males (p = .1) and females (p = .3). For cases overall, there was a preponderance of intestinal type of gastric cancer (76.5%). No significant trend over time was observed in the mean rate of occurrence of intestinal or diffuse type of gastric cancer. The ratio of intestinal: diffuse was 6.5 for all ages. Among males, a significant (p = .03) upward trend in the incidence was observed for proximal tumours, while no such trend (p = .07) was observed among women. A significant decline in incidence of distal tumours was observed for males (p = .000) and females (p.007). Male:Female ratio for proximal tumour was 4.7:1. The results suggests that Tasmanians may have been a population at high risk of gastric cancer.

Fracture of the sternum--an unusual case

Stress fracture of the sternum is a rare injury and can occur in young athletes due to repeated stress and in elderly with osteoporotic bones or other pathological conditions under normal stress. A case of a 14-year-old boy is reported who sustained fracture of the sternum without any history of significant trauma when he simply tried to lift his whole body over his arms and felt pain in front of the chest.

Inter-hospital comparison of mortality rates

OBJECTIVE

To compare crude and adjusted in-hospital mortality rates after prostatectomy between hospitals using routinely collected hospital discharge data and to illustrate the value and limitations of using comparative mortality rates as a surrogate measure of quality of care.

METHODS

Mortality rates for non-teaching hospitals (n = 21) were compared to a single notional group of teaching hospitals. Patients age, disease (comorbidity), length of stay, emergency admission, and hospital location were identified using ICD-9-CM coded Victorian hospital morbidity data from public hospitals collected between 1987/88 and 1994/95. Comparisons between hospitals were based on crude and adjusted odds ratios (OR) and 95% confidence intervals (CI) derived using univariate and multivariate logistic regression. Model fit was evaluated using receiver operating characteristic curve i.e. statistic, Somer's D, Tau-a, and R2.

RESULTS

The overall crude mortality rates between hospitals achieved borderline significance (alpha2=31.31; d.f.=21; P=0.06); these differences were no longer significant after adjustment (chi2=25.68; P=0.21). On crude analysis of mortality rates, four hospitals were initially identified as 'low' outlier hospitals; after adjustment, none of these remained outside the 95% CI, whereas a new hospital emerged as a 'high' outlier (OR=4.56; P= 0.05). The adjusted ORs between hospitals compared to the reference varied from 0.21 to 5.54, ratio = 26.38. The model provided a good fit to the data (c=0.89; Somer's D= (0.78; Tau-a = 0.013; R2= 0.24).

CONCLUSIONS

Regression adjustment of routinely collected data on prostatectomy from the Victorian Inpatient Minimum Database reduced variance associated with age and correlates of illness severity. Reduction of confounding in this way is a move in the direction of exploring differences in quality of care between hospitals. Collection of such information over time, together with refinement of data collection would provide indicators of change in quality of care that could be explored in more detail as appropriate in the clinical setting.

Adverse events after prostatectomy in Victorian public hospitals

BACKGROUND

A retrospective analysis of data from the Victorian Inpatient Minimum Database (VIMD) was conducted to analyse trends in prostatectomy rates in Victorian public acute-care hospitals from 1989/90 to 1994/95. The study also sought to identify predictors of adverse events (AE) after prostatectomy, and to compare in-hospital complications between open prostatectomy and transurethral resection of prostate (TURP).

METHODS

All patients who had undergone any prostatectomy were identified according to the relevant ICD-9-CM procedure codes (60.2-60.4) documented in the VIMD. The main outcome measures, AE, were identified using the ICD-9-CM supplementary classification of external cause of injury (E850-858, E870-876, E878-879, E930-949). The variables used as predictors were year of prostatectomy, type of admission (planned, emergency), location of the hospital (rural, metropolitan), type of procedure (TURP, open), and teaching status of the hospital. Crude and adjusted odds ratios (OR) were based on univariate and multivariate logistic regression.

RESULTS

The rates of prostatectomies have significantly increased over the 6-year study period (P for trend < 0.0001). The percentage of AE after prostatectomy increased simultaneously from 6.1 to 12.9% (P < 0.0001). During the same period, the in-hospital mortality rate after prostatectomy decreased from 1.2 to 0.5%, and length of stay decreased from 10.3 to 6.1 days (Kruskal-Wallis P < 0.0001). The significant predictors of outcome were year of prostatectomy (P for trend < 0.0001), emergency admissions (OR = 1.57; P < 0.0001), metropolitan hospitals (OR = 0.81; P = 0.0003), non-teaching hospitals (OR = 0.78; P < 0.0001), and open prostatectomy (OR = 1.52; P = 0.04). More in-hospital complications were associated with open prostatectomy than with TURP.

CONCLUSIONS

The rise in AE rate after prostatectomy is unlikely to reflect poor quality of care, because in the same period there was a significant decrease in in-hospital mortality after prostatectomy. A more likely explanation is heightened awareness of AE with a lower threshold for reporting such events. Important factors other than variations in quality of care can result in an increase in AE. Hence the reported increase should be interpreted with caution before attempting to conclude that changes in clinical practice could have a direct impact on these rates.

Predictors of length of stay for transurethral prostatectomy in Victoria

BACKGROUND

Transurethral resection of prostate (TURP) is among the top 10 surgical conditions that account for hospital admission in Victoria. Bed utilization for TURP is an increasing concern in current times. This paper describes trends in length of stay (LOS) and identifies predictors of LOS for TURP in Victoria.

METHODS

Trends in TURP were studied using ICD-9-CM coded Victorian hospital morbidity data from public hospitals from 1987/88 to 1994/95. Detailed morbidity data from the same source for the financial year 1995/96 were used to study predictors of LOS by logistic regression.

RESULTS

Length of stay decreased significantly between 1987 and 1995 from 10.6 to 6.1 days. The strongest predictor of increased LOS was admission through the emergency room (odds ratio (OR) 14.7; 95% confidence interval (CI) 11.8-18.3). Other significant predictors were older age, lower socio-economic status, presence of comorbid conditions, occurrence of procedural morbidity, and hospital type and location.

CONCLUSIONS

The trend in decreasing LOS may be explained by increasingly efficient bed management in hospitals who are faced with an increasing need for cost control. Advances in surgical techniques and peri-operative care have also contributed to the decrease in LOS. Other factors that influence LOS can be divided into three categories: intrinsic patient factors, such as co-morbid conditions; procedure-specific factors such as peri-operative morbidity; and intrinsic hospital factors relating to capacity and resources. Such determinants of LOS may be of value to policy makers when considering the effective application of newer methods for treatment of benign prostatic hyperplasia.

Congestive cardiac failure (CCF) as a cause of fatal stroke and all cause death

BACKGROUND

Congestive cardiac failure (CCF) has been found to be a clinical risk factor for stroke in patients with non rheumatic atrial fibrillation.

AIMS

To study CCF as a risk factor for stroke deaths and all cause deaths in coronary heart disease (CHD).

METHODS

Case control study from a single cardiologist's practice: 370 deaths, 32 (9%) from stroke; controls of 160 and 370 consecutive patients for stroke deaths and all cause deaths respectively. Multivariate analysis using logistic regression.

RESULTS

A--Stroke deaths. Positive associations for CHD with CCF, hypertension; negative association for CHD without CCF. Patients with CHD and CCF were 7.4 times as likely to die from stroke as patients with CHD without CCF. B--All cause deaths. Positive associations for CHD or cardiomyopathy with CCF, atrial fibrillation, diabetes and hypertension; negative association for CHD without CCF. Patients with CHD and CCF were 6.1 times as likely to die from all causes as patients with CHD without CCF.

CONCLUSIONS

Many stroke deaths in patients with CHD and CCF may be cardioembolic in origin. A randomised controlled trial in such patients is indicated to see if anticoagulants can reduce the incidence of stroke.

Oscillating saw injuries during removal of plaster

The aim of this study was to assess the incidence of injuries to patients who have had a plaster cast removed by oscillating circular saw at the Alexandra Hospital, Redditch, and to recommend measures to avoid such injuries. The record of each patient who had his/her plaster removed was kept in the plaster room and later studied. Over a 12-month period (1995-96), 3875 plaster casts were removed; 28 patients (0.72%) sustained abrasions or burns over the skin. Recently there has been a sudden rise in the number of cases who sustained injury or burns by oscillating saw following plaster cast removal and a few patients have demanded compensation from the hospital. These incidences prompted the start of this study. The identified cause of injury was the removal of a plaster cast by an inexperienced, ill-trained user or blunt saw blade. Strict protocols were required and have been introduced at the Alexandra Hospital to avoid litigation.

Lipid levels and peripheral vascular disease in diabetic and non-diabetic subjects

Non-insulin dependent diabetes (NIDDM) is associated with an increased risk of peripheral vascular disease (PVD), but within the diabetic population the relationship between lipid profile and PVD has not been clearly defined. In this study we examined the association of lipid parameters and in particular low density lipoprotein (LDL) particle size, with the presence of PVD in subjects with and without NIDDM. 41 NIDDM patients and 31 non-diabetic subjects with PVD in the absence of rest pain or ulceration, defined by ankle-brachial index measurements and duplex scanning, were compared with 41 NIDDM and 31 euglycemic control subjects of comparable age and sex, without PVD. In both groups those with PVD were found to have significantly elevated triglycerides (2.7 [2.2-3.3] versus 1.9 [1.6-2.2] mmol/l; P < 0.05 in the diabetic group and 2.0 [1.6-2.3] versus 1.4 [1.1-1.5] mmol/l; P < 0.05 in the non-diabetic group), decreased apolipoprotein A1 (124 +/- 3 versus 139 +/- 5 mg/dl; P < 0.01 in the diabetic group and 133 +/- 4 versus 147 +/- 4 mg/dl; P < 0.05 in the non-diabetic group) and decreased LDL particle size (25.4 +/- 0.1 versus 25.8 +/- 0.1 nm; P < 0.01 in the diabetic group and 26.0 +/- 0.1 versus 26.3 +/- 0.1 nm; P < 0.05 in the non diabetic group). In the non-diabetic group apolipoprotein[a] (365 [239-554] versus 184 [17-266] U/l; P < 0.01), total cholesterol (6.3 +/- 0.2 versus 5.6 +/- 0.2 mmol/l; P < 0.05), LDL cholesterol (4.1 +/- 0.2 versus 3.6 +/- 0.2 mmol/l; P < 0.05) and apolipoprotein B (146 +/- 8 versus 117 +/- 5 mg/dl; P < 0.05) were also found to be associated with PVD although these associations were not observed in the group with diabetes. In addition, 11 NIDDM subjects and 11 non-diabetic subjects with rest pain or ulceration were compared to the corresponding groups with uncomplicated PVD and had lipid profiles with significantly lower levels of total cholesterol and LDL cholesterol. We conclude that the dyslipidemic profile characterized by increased triglyceride level, decreased apolipoprotein A1 level and small dense LDL is associated with uncomplicated PVD in both NIDDM and non-diabetic subjects.

Nosocomial infection indicators in Australian hospitals: assessment according to hospital characteristics

The relationship of bed size and hospital type (private or public) was studied using Hospital-Wide Medical Indicator data on nosocomial infections submitted to the Australian Council on Healthcare Standards Care Evaluation Program by hospitals presenting voluntarily for accreditation in 1993. The aim was to determine if this process could simplify the establishment of hospital peer groups for comparison of risk in the absence of knowledge of patient illness severity indices. After adjusting for potential confounders in a logistic model, hospital type was found to be a significant predictor for the occurrence of infection in clean and contaminated wounds. Bed size was a significant predictor for the occurrence of hospital-acquired bacteraemia in private and public hospitals. The increase in the risk of developing hospital acquired bacteraemia with increasing number of beds was significant as a trend (P < 0.0001) in private as well as public hospitals. The results suggest that hospital type and bed size are initial indices for 'flagging' peer group variation and prompting a more detailed internal review.

Postoperative complications of cholecystectomy in Victorian public hospitals

Cholecystectomies in Victorian public hospitals were evaluated by analysis of hospital morbidity data. The Victorian Inpatient Minimum Dataset (VIMD) contains data on postoperative complications from all cholecystectomies in Victorian public hospitals. Hospital separations associated with cholecystectomy were identified according to Australian national diagnosis-related groups and the procedures were grouped as open, laparoscopic or conversion from laparoscopic to open cholecystectomy (conversion). Postoperative complications were identified by ICD9-CM external-cause codes (E-codes) in the VIMD. The 35593 cholecystectomies performed between 1987-88 and 1993-94 were analysed. A further detailed analysis of all cholecystectomies performed in 1993 was based on logistic regression. This identified the adjusted odds (AOR) of occurrence of complications and included covariates of age, sex, admission type, diagnosis-related group and hospital identification code. The annual frequency of cholecystectomy increased after introduction of laparoscopic cholecystectomy in 1990, and was associated with an increase in rates of separations having adverse events, but laparoscopic cholecystectomy had the lowest rate (66.7 per 1000 separations). Adverse-event rates for open procedures increased to 157.5 per 1000 in 1993-94, and for conversions to 290.0 per 1000. Of 5627 cholecystectomies in 1993, 74.4 per cent were laparoscopic, 21.5 per cent open and 4.1 per cent conversions. Postoperative complications were more likely in males (AOR 1.67, 95 per cent confidence interval (CI) 1.38 to 2.04), in patients admitted as an emergency (1.27, CI 1.01 to 1.60), and in those having open cholecystectomies (2.25, 1.78 to 2.85) or conversions (4.29, 3.05 to 6.03). Analysis of the VIMD has provided information for the evaluation of cholecystectomy. The VIMD is a useful tool for monitoring postoperative complications and the quality of care in Victorian hospitals.

Establishing thresholds for adverse patient outcomes

OBJECTIVE

To establish thresholds for adverse patient outcomes in the absence of knowledge of patient illness severity indices.

OUTCOMES

Pulmonary embolism, unplanned return to operating rooms, unplanned readmissions, clean and contaminated wound infections, and hospital-acquired bacteraemia.

DESIGN

Analysis of results of surveys of hospitals in Australia by the Australian Council on Healthcare Standards following the introduction of clinical performance measures into the Accreditation process.

SETTING

Acute care hospitals in Australia undergoing Accreditation surveys in 1993 and 1994.

METHODS

Stratification of hospitals into small (1-99 beds), medium (100-199 beds), and large (> or = 200 beds), calculation of mean rates for the above outcomes in each group, and establishment of thresholds based on two standard errors from the mean.

RESULTS

The mean rate of occurrence of incidents was higher for larger hospitals. Thresholds were generally lower for smaller and higher for larger hospitals.

CONCLUSIONS

Bed-size is a useful index for "flagging" peer group variation. The methodological issues in establishing thresholds and their implications in monitoring the quality of care in hospitals are discussed.

The risk of an unplanned return to the operating room in Australian hospitals

BACKGROUND

The unplanned return of the patient to the operating room (OR) after a previous procedure has implications concerning the quality of surgery, but little has been written on this subject.

METHODS

The relationship of bed-size and hospital type (private or public) was studied using data on this clinical indicator submitted to the Australian Council on Healthcare Standards Care Evaluation Program (ACHS CEP) by hospitals presenting voluntarily for accreditation in 1993.

RESULTS

The mean rate of an unplanned return to OR was 0.6% (95% confidence interval 0.5-0.7). After adjusting for potential confounders in a logistic model, the risk of unplanned return to OR did not significantly differ by type of hospital (private or public), and location (rural, metropolitan). The risk of unplanned return to OR was higher in large compared with small hospitals.

CONCLUSIONS

The finding of the risk of the event being greater in large compared with small hospitals is likely to be a reflection of casemix. An interval review of results (for any facility) is obviously necessary. With some operations a higher incidence of return to the OR may indicate vigilance in peri-operative management.

The Australian Council on Healthcare Standards care Evaluation Program

With the assistance of the medical colleges, the Australian Council on Healthcare Standards (ACHS), through its Care Evaluation Program, has established clinical performance measures which will assist both internal and external review of care and enable hospitals to compare their quality of patient care with that of other hospitals.

Errors in drug prescribing

This study reports on early results following the introduction of one measure of medication prescription errors, that being the prescribing of a drug for which there is an 'alert' notice, into The Australian Council on Healthcare Standards Accreditation process. Characteristics of hospitals reporting of zero and non-zero errors were analysed using a logistic model. After adjusting for other hospital characteristics and duration of data collection, hospitals over 100 beds were more likely to report medication errors compared to hospitals with 1-100 beds. Reporting of these prescribing errors was not associated with the particular type or location of the hospital. However, as a result of monitoring of this indicator, a number of hospitals reported an increase in their quality assurance activities. It is a sentinel event and not a rate based indicator and, as a performance measure, is of greater value as an internal, rather than external, review mechanism.

Epidemiology of eclampsia

The purpose of this study was to examine the risk of eclampsia in relation to several maternal characteristics and exposures, including demographic characteristics, reproductive history, and tobacco use during pregnancy. A case control study was conducted using data for all singleton births from the Washington State birth certificates for 1984-1990. In the check box feature employed by these certificates, eclampsia is listed under maternal conditions. Risk estimates, adjusted for various confounders, were calculated comparing eclampsia among exposed versus unexposed women. The risk of eclampsia was elevated in women without prenatal care, those with weight gain of more than thirty pounds during pregnancy, nulliparous women, and those with chronic hypertension. The association with tobacco smoking were inverse and dose related. Women's race, urban or rural place of residence, history of pre-term births, and anemia were not associated with eclampsia. Our data reaffirm the importance of prenatal care, and provide further evidence of an inverse relationship with prenatal smoking. As eclampsia and pre-eclampsia are important pregnancy complications, further research is needed to explore their possible causes.

Assessment of postoperative pulmonary embolism as a measure of patient care

Hospitals presenting voluntarily for accreditation survey during 1993 submitted data on pulmonary embolism to the Australian Council on Health Care Standard (ACHS) Care Evaluation Program (CEP) as a part of their medical quality activities. The data were stratified by hospital type and bed-size, and compared to the provisional threshold of 1%. The mean duration of data collection was 24 weeks (range 8-74 weeks). Of hospitals with bed-size 1-50, 77% observed a zero pulmonary embolism rate. Hospitals with zero and non-zero pulmonary embolism rates were significantly different with respect to bed-size (P = 0.001). The rarity of pulmonary embolism and lack of prospective continuous monitoring poses considerable problems in interpretation of aggregate rates. Hospitals with a high patient throughout should continuously monitor their pulmonary embolism data to achieve a large denominator. For smaller hospitals with a low performance of major operations, collection of data on this clinical indicator is unlikely to be useful as a measure of quality of care.

Hospital characteristics associated with unplanned readmissions

The rate of unplanned readmission of patients to hospitals has been introduced into the Australian Council on Healthcare Standards accreditation program as an internal flag of problems in patient management and outcome. An emphasis, in the indicator definition, is placed on the unexpected nature of the admissions to exclude those which are unplanned but simply due to progression of a disease, and are therefore not 'unexpected'. The association of hospital characteristics with unplanned readmissions was examined using logistic regression on the data collected from hospitals surveyed in 1993. The risk of unplanned readmission was significantly higher in public hospitals than in private hospitals. Hospital bed-size also reflected differences in the risk of unplanned readmission, being significantly higher for hospitals with over 200 beds than for those with 1-100 beds. In rural areas, the risk of unplanned readmission was significantly lower in hospitals with 101-200 beds and over 200 beds compared to hospitals with 1-100 beds (p for trend = .004). However, in metropolitan areas, the risk of unplanned readmission increased with the size of the hospitals (p for trend < .0001). Monitoring of unplanned readmissions prompted internal clinical review and action in 31 per cent of hospitals, demonstrating the indicator's usefulness as an internal quality tool. However, the use of unplanned readmissions as an external performance measure must take into account a hospital's characteristics and will remain of limited value in the absence of clinical information about the expected or unexpected nature of the readmissions.

Higher lung cancer rates in young women than young men: Tasmania, 1983 to 1992

In a background of changing lung cancer rates in the past decade, mean incidence and mortality rates for persons aged 25-44 in Tasmania for the decade 1983 through 1992 were examined using Tasmanian Cancer Registry data. The smoking behavior of Tasmanian adults and schoolchildren was also investigated, using data from a social survey conducted by the Australian Bureau of Statistics and from five secondary school smoking surveys. The Tasmanian age-standardized lung cancer incidence rates in 25-44 year olds for the 10-year period were 6.2 per 100,000 females and 3.3 per 100,000 males. Mean rates of incidence were higher for females than for males (P = 0.02). The corresponding mortality rates were 4.2 in females and 2.4 in males (P = 0.08). The prevalence of smoking by adult Tasmanian women is higher than that for other Australian women (P < 0.05), and their duration of smoking is longer (P < 0.01). Tasmanian schoolgirls have a higher smoking prevalence than Australian mainland schoolgirls (P = 0.01) and higher prevalence than Tasmanian schoolboys (P = 0.01). The data suggest that smoking prevalence among teenagers passed that for males only a decade before the observed excess of female incident cases among 25-44 year olds in Tasmania.

Evaluation of vero cell lysate antigen for the ELISA of flaviviruses

The vero cell lysate antigen for the enzyme-linked immunosorbent assay (ELISA) of flaviviruses was evaluated for sensitivity, specificity including cross-reactions, and background by comparing with the standard ELISA. Human sera, in serial dilutions, were taken from subjects 14, 35, and 210 days postvaccination with 17D antigen. Early after injection, high sensitivity (82.9%) was shown by the cell lysate antigen method. Late after infection, high sensitivity was achieved by the standard method (96.2% and 94%), with significant difference (P = 0.0001). However, sensitivity achieved by the cell lysate antigen method was also acceptable (91.7% & 88.9%). The cell lysate antigen method showed high specificity and low cross reactivity early after infection. At 35 days postvaccination, no difference in specificity was observed between the two methods, but higher cross-reactions were observed for the standard method. This pattern continued at 210 days postvaccination, with significantly higher cross-reactions with the standard ELISA. The optical density differences by the two methods did not show significant relationship with the serial dilutions of human sera. No difference was observed in early and late infections in the background values of the negative control (Western equine encephalitis) between the two methods. The ELISA by the cell lysate antigen, within the limits of the experiments done, was found to be a good replacement for the ELISA by the standard method.

Studies on the development and survival periods of the non-parasitic stages of Boophilus microplus (Canestrini), in the climatic conditions of Ranchi (India)

Engorged female ticks of Boophilus microplus were exposed in wire-gauze cylinders and glass tubes in an experimental grass plot at monthly intervals during 1989, and egg laying, egg development and larval survival periods observed and recorded. Rainfall and atmospheric relative humidity had an important influence on tick activity. Egg production was maximum, hatching percentage was high, incubation and prehatch periods were short, and larval survival and total longevity periods were long for ticks exposed during the warm and humid rainy season from June to September. Dry atmospheric conditions severely affected egg development, egg hatch and larval survival. Eggs failed to hatch in the dry months from December to April and only 29-38% hatched after a long incubation period of 41 days in November and May. On grass, the larvae of ticks exposed in November survived for the shortest period of 28 days and the larvae of ticks exposed in June survived for the longest period of 133 days. Low winter temperatures reduced egg production and prolonged the pre-oviposition, oviposition and incubation periods. It is suggested that the results of this study might be helpful in the development of measures to control tick infestation by planned dipping and restricted grazing during the period from late June to January when the pasture has a substantial load of larval ticks.

Clinico-biochemical use of serum acetylcholine esterase following treatment with synthetic pyrethroids, cypermethrin and fenvalerate, in cattle and buffalo experimentally infested with Boophilus microplus

Following treatment, cypermethrin and fenvalerate, were found to have inhibitory effect on serum acetylcholine esterase (AchE) activity of cattle and buffalo experimentally infested with B. microplus. The pattern of AchE activity in infested-pyrethroid-treated group was found to be significantly different from either healthy or tick-infested control. There was transient increase in the enzyme activity initially, followed by gradual decline and subsequent increase leading to normal level within 7 days of pyrethroid treatment. The enzyme activity was found to be low in buffalo than in cattle and the values remained below normal level up to day 7 in tick-infested group. The reversion of AchE activity to normal level in pyrethroid-treated group indicated that these compounds are prompt and safe ixodicides with least residual effect. The present investigation concludes that estimation of serum AchE might help in the clinico-biochemical diagnosis of tick toxin and pyrethroid toxicity in cattle and buffalo treated with these pyrethroids against tick infestation.