The clustering of health risk behaviours in a Western Australian adult population

ISSUE ADDRESSED

Human behaviours influence health. Most people partake in numerous behaviours that increase their risk of chronic disease. For years health promotion interventions have been changing behaviour to improve health. While it is known that most people exhibit more than one health risk behaviour, it is not clear if health behaviours occur in patterns within population subgroups. This paper aims to explore the clustering patterns of six health risk behaviours among Australian adults.

METHODS

Data collected from four (1992, 1994, 1998 and 2002) community-based surveys were used to explore the relationships between a variety of health risk behaviours. The behaviours included were smoking, unsafe alcohol consumption, low fruit consumption, low vegetable consumption, insufficient physical activity and poor sun protection practices. The sample comprised 8,668 West Australian residents aged 16-69 years. A k-means cluster analysis was used to determine groups of people with similar health behaviours.

RESULTS

Four health risk behaviour clusters were identified, one overall health promoting 'Safe', two 'Risky' and one 'Moderate' (mix of healthy and unhealthy behaviours). These health behaviour clusters were distinguishable by demographic characteristics, where by women aged 40 years and older on high incomes were most likely to be part of the 'Safe' cluster, younger people the risky smoker cluster and older men the risky drinker cluster.

CONCLUSION

The results of this study support the idea that people exhibit on average three risky health behaviours and that these behaviours inter-relate. The results further suggest that sub-groups in the study population were differentiated by the type of risky health behaviours they exhibit.

Long term survival after evidence based treatment of acute myocardial infarction and revascularisation: follow-up of population based Perth MONICA cohort, 1984-2005

OBJECTIVE

To examine trends in long term survival in patients alive 28 days after myocardial infarction and the impact of evidence based medical treatments and coronary revascularisation during or near the event.

DESIGN

Population based cohort with 12 year follow-up.

SETTING

Perth, Australia.

PARTICIPANTS

4451 consecutive patients with a definite acute myocardial infarction according to the World Health Organization MONICA (monitoring trends and determinants in cardiovascular disease) criteria admitted to hospital during 1984-7, 1988-90, and 1991-3.

MAIN OUTCOME MEASURES

All cause mortality identified from official mortality records and the hospital morbidity data, with death from cardiovascular disease as a secondary end point.

RESULTS

In the 1991-3 cohort, 28 day survivors of acute myocardial infarction had a 7.6% absolute event reduction (95% confidence interval 4% to 11%) or a 28% lower relative risk reduction (16% to 38%), unadjusted for risk of death, over 12 years after the incident admission compared with the 1984-7 cohort, similar to the survival of the 1988-90 cohort. The improved survival for the 1991-3 cohort persisted after adjustment for demographic factors, coronary risk factors, severity of disease, and event complications with an adjusted relative risk reduction of 26% (14% to 37%), but this was not apparent after further adjustment for medical treatments in hospital and coronary revascularisation procedures within 12 months of the incident myocardial infarction.

CONCLUSION

The improving trends in 12 year survival after a definite acute myocardial infarction are associated with progressive use of evidence based treatments during the initial admission to hospital and in the 12 months after the event. These changes in the management of acute myocardial infarction are probably contributing to the continuing decline in mortality from coronary heart disease in Australia.

The effect of socioeconomic status on outcomes for seriously ill patients: a linked data cohort study

OBJECTIVE

To investigate the association between socioeconomic status (SES) and outcomes for seriously ill patients.

DESIGN AND SETTING

A retrospective cohort study based on data from an intensive care unit clinical database linked with data from the Western Australian hospital morbidity and mortality databases over a 16-year period (1987-2002).

MAIN OUTCOME MEASURES

In-hospital and long-term mortality.

RESULTS

Data on 15,619 seriously ill patients were analysed. The in-hospital mortality rate for all seriously ill patients was 14.8%, and the incidence of death after critical illness was 7.4 per 100 person-years (4.8 per 100 person-years after hospital discharge). Patients from the most socioeconomically disadvantaged areas were more likely to be younger, to be Indigenous, to live in a remote area, to be admitted non-electively, and to have more severe acute disease and comorbidities. SES was not significantly associated with in-hospital mortality, but long-term mortality was significantly higher in patients from the lowest SES group than in those from the highest SES group, after adjusting for age, ethnicity, comorbidities, severity of acute illness, and geographical accessibility to essential services (hazard ratio for death in lowest SES group v highest SES group was 1.21 [95% CI, 1.04-1.41]; P = 0.014). The attributable incidence of death after hospital discharge between patients from the lowest and highest SES groups was 1.0 per 100 person-years (95% CI, 0.3-1.6 per 100 person-years).

CONCLUSION

Lower SES was associated with worse long-term survival after critical illness over and above the background effects of age, acuity of acute illness, comorbidities, Indigenous status and geographical access to essential services.

Tracking of pedometer-determined physical activity in adults who relocate: results from RESIDE

Background

This secondary analysis investigated the extent and pattern of one-year tracking of pedometer-determined physical activity in people who relocated within the same metropolitan area (T1: baseline and T2: post-relocation). Specifically, data were derived from the RESIDential Environment Project (RESIDE), a natural experiment of people moving into new housing developments.

Methods

1,175 participants (491 males, age = 42.6 ± 12.7 years, BMI = 27.2 ± 9.9 kg/m²; 684 females, age = 41.2 ± 11.3 years, BMI = 25.4 ± 5.2 kg/m²) wore a Yamax pedometer (SW-200-024) for seven days during the same season at both time points. Pearson's product-moment and Spearman's rank order correlations were used to evaluate the extent of tracking of mean steps/day. Age categories were set as youngest-29.9 (19 was the youngest in males, 20 in females), 30–39.9, 40–49.9, 50–59.9, and 60-oldest (78 was the oldest in males, 71 in females). Change in steps/day was also described categorically as: 1) stably inactive < 7,500 steps/day; 2) decreased activity (moved from ≥ 7,500 to < 7,500 steps/day between T1 and T2); 3) increased activity (moved from < 7,500 to ≥ 7,500 steps/day between T1 and T2); and, 4) stably active ≥ 7,500 steps/day at both time points. Stratified analyses were used to illuminate patterns by sex, age, and BMI-defined weight categories.

Results

Overall, there was a small (non-significant) decrease in steps/day between T1 and T2 (mean ± SD is -81 ± 3,090 with 95%CI -259 to 97). With few exceptions (i.e., older women), both Pearson's and Spearman's correlations were moderate (r = 0.30–0.59) to moderately high (r = 0.60–0.70). The relative change/stability in steps/day (cut at 7,500 steps/day) was not significant across age groups in males (χ² = 17.35, p = .137) but was in females (χ² = 50.00, p < .0001). In both males and females the differences across BMI categories was significant (χ² = 22.28, p = .001 and χ² = 15.70, p = .015, respectively). For both sexes, those in the obese category were more stably inactive (and less stably active) between assessment points compared with those who were categorized as normal weight.

Conclusion

Despite relocation, Western Australian adults held their rank position to a moderate to moderately high extent over one year. Categorized and expressed as relative stability/change over time, sex, age, and BMI patterns were evident.

Are the associations between diet and C-reactive protein independent of obesity?

OBJECTIVES

To determine the relative magnitude of the effect of dietary factors on circulating C-reactive protein (CRP) levels, controlling for BMI.

METHODS

1808 men and 2269 women attended the 1994/95 follow-up survey from the Busselton Health Study, Australia. A composite diet score was derived from a short questionnaire. Height and weight were measured.

RESULTS

After controlling for BMI, CRP levels were associated with red meat intake (males only, p=0.001), fruit intake (males p<0.0001, females p=0.029), potato intake (males p=0.008, females p=0.029), using wholemeal bread (males p=0.014, females p=0.018), using polyunsaturated fats as a spread and in cooking (females only, p=0.005), and rarely or never adding salt to food (males p=0.012, females p=0.004). The overall diet score was significantly (negatively) related to CRP in males (p<0.0001) and females (p<0.0001). The relative decrease in CRP from a moderately healthy diet, compared to an unhealthy diet was 37% in men and 24% in women. This was comparable to a difference in BMI of at least 3 kg/m(2) (or a difference in weight of approximately 9 kg for a person of average height).

CONCLUSION

A healthy diet and lower weight have independent beneficial effects of similar magnitude on CRP levels.

Adapting a Markov Monte Carlo simulation model for forecasting the number of coronary artery revascularisation procedures in an era of rapidly changing technology and policy

BACKGROUND

Treatments for coronary heart disease (CHD) have evolved rapidly over the last 15 years with considerable change in the number and effectiveness of both medical and surgical treatments. This period has seen the rapid development and uptake of statin drugs and coronary artery revascularization procedures (CARPs) that include Coronary Artery Bypass Graft procedures (CABGs) and Percutaneous Coronary Interventions (PCIs). It is difficult in an era of such rapid change to accurately forecast requirements for treatment services such as CARPs. In a previous paper we have described and outlined the use of a Markov Monte Carlo simulation model for analyzing and predicting the requirements for CARPs for the population of Western Australia (Mannan et al, 2007). In this paper, we expand on the use of this model for forecasting CARPs in Western Australia with a focus on the lack of adequate performance of the (standard) model for forecasting CARPs in a period during the mid 1990s when there were considerable changes to CARP technology and implementation policy and an exploration and demonstration of how the standard model may be adapted to achieve better performance.

METHODS

Selected key CARP event model probabilities are modified based on information relating to changes in the effectiveness of CARPs from clinical trial evidence and an awareness of trends in policy and practice of CARPs. These modified model probabilities and the ones obtained by standard methods are used as inputs in our Markov simulation model.

RESULTS

The projected numbers of CARPs in the population of Western Australia over 1995-99 only improve marginally when modifications to model probabilities are made to incorporate an increase in effectiveness of PCI procedures. However, the projected numbers improve substantially when, in addition, further modifications are incorporated that relate to the increased probability of a PCI procedure and the reduced probability of a CABG procedure stemming from changed CARP preference following the introduction of PCI operations involving stents.

CONCLUSION

There is often knowledge and sometimes quantitative evidence of the expected impacts of changes in surgical practice and procedure effectiveness and these may be used to improve forecasts of future requirements for CARPs in a population.

Bayesian approach to predict hospital mortality of intensive care readmissions during the same hospitalisation

No specific prognostic model has been developed for patients readmitted to the intensive care unit (ICU) during the same hospitalisation. This study assesses the performance of the Acute Physiology and Chronic Health Evaluation (APACHE) II predicted mortality measured at the time of ICU readmission and whether incorporating information prior to the readmission will improve its performance to predict hospital mortality of patients readmitted to ICU during the same hospitalisation. A total of 602 readmissions during the same hospitalisation between 1987 and 2002 were identified. The first admission APACHE II predicted mortality was significantly associated with the hospital mortality only in the subgroup of patients readmitted within seven days of ICU discharge (odds ratio 1.16, 95% confidence interval 1.01 to 1.34; P = 0.035). In the subgroups of patients readmitted within seven days of discharge, the readmission APACHE II predicted mortality was also significantly better than the first admission APACHE II predicted mortality in discriminating between survivors and non-survivors (area under the receiver operating characteristic curve: 0.785 vs. 0.676, z statistic = 2.93; P = 0.003). Incorporating the first admission APACHE II predicted mortality to the readmission APACHE II predicted mortality, either by multilevel likelihood ratios or logistic regression, did not significantly improve its discrimination (area under the receiver operating characteristic curve: 0.792 vs. 0.785, z statistic = 0.52; P = 0.603). Our results suggested that information on prior ICU admission during the same hospitalisation is not as important as the severity of illness measured at the time of readmission in determining the mortality of intensive care readmissions during the same hospitalisation.

Do aggregates of multiple questions better capture overall fish consumption than summary questions?

Objective

To compare intake estimates, validity and reliability of two summary questions to measure fish consumption with information from a detailed semi-quantitative food-frequency questionnaire (FFQ) on fish consumption.

Design

Population-based, cross-sectional study. Participants completed an FFQ and provided blood samples for erythrocyte membrane eicosapentaenoic acid (EPA) analysis. Aggregate measures of consumption of fresh/frozen/canned fish (fresh fish) and smoked/salted/dried fish (preserved fish) were generated from the FFQ and were compared with responses to the summary questions regarding intakes of similar items. Both methods were tested for validity, using correlation and linear regression techniques with EPA, and retest reliability.

Setting

Perth metropolitan area, Western Australia.

Subjects

One hundred and nine healthy volunteers of both sexes, aged 21–75 years.

Results

The summary fresh fish measure underestimated frequency and grams per week given by the aggregate question by about 50%, while estimates from the summary preserved fish measure were approximately three times that of the aggregate measure. Multiple linear regression analysis suggested that the aggregates accounted for more of the variation in EPA levels, but the difference was minimal. Intra-class correlations confirmed that both methods were reliable.

Conclusions

Our study indicates that extensive questioning results in different absolute intakes of fish compared with brief questioning, but does not add any information if ranking individuals according to overall consumption of fish.

Evaluation of the implementation of a state government community design policy aimed at increasing local walking: design issues and baseline results from RESIDE, Perth Western Australia

OBJECTIVES

To describe the design and baseline results of an evaluation of the Western Australian government's pedestrian-friendly subdivision design code (Liveable Neighborhood (LN) Guidelines).

METHODS

Baseline results (2003-2005) from a longitudinal study of people (n=1813) moving into new housing developments: 18 Liveable, 11 Hybrid and 45 Conventional (i.e., LDs, HDs and CDs respectively) are presented including usual recreational and transport-related walking undertaken within and outside the neighborhood, and 7-day pedometer steps.

RESULTS

At baseline, more participants walked for recreation and transport within the neighborhood (52.6%; 36.1% respectively), than outside the neighborhood (17.7%; 13.2% respectively). Notably, only 20% of average total duration of walking (128.4 min/week (SD159.8)) was transport related and within the neighborhood. There were few differences between the groups' demographic, psychosocial and perceived neighborhood environmental characteristics, pedometer steps, or the type, amount and location of self-reported walking (p>0.05). However, asked what factors influenced their choice of housing development, more participants moving into LDs reported aspects of their new neighborhood's walkability as important (p<0.05).

CONCLUSIONS

The baseline results underscore the desirability of incorporating behavior and context-specific measures and value of longitudinal designs to enable changes in behavior, attitudes, and urban form to be monitored, while adjusting for baseline residential location preferences.

Understanding dog owners' increased levels of physical activity: results from RESIDE

We examined the influence of dog ownership on physical activity, independent of demographic, intrapersonal, and perceived environmental factors, in a cross-sectional survey of 1813 adults. Although only 23% of the dog owners walked their dogs 5 or more times per week, the adjusted odds of achieving sufficient physical activity and walking were 57% to 77% higher among dog owners compared with those not owning dogs (P< .05). Dog ownership was independently associated with physical activity and walking. Actively encouraging more dog walking may increase community physical activity levels.

A Markov simulation model for analyzing and forecasting the number of coronary artery revascularization procedures in Western Australia

PURPOSE

A Markov chain Monte Carlo simulation model was developed to analyze and forecast the numbers of coronary artery bypass graftings, percutaneous coronary interventions (PCIs) , incident coronary heart disease (CHD) events, and CHD deaths for different age and sex groups in the population of Western Australia (population approximately 1.7 million).

METHODS

The Western Australian health information system contains linked records of all hospital admissions and deaths for individuals from 1980 to the present. This system allows the separation of the population into groups according to CHD/coronary artery revascularization procedure history and also allows the estimation of event probabilities directly from population-level data.

RESULTS AND CONCLUSIONS

The results for the 1990 Western Australian population over the period 1990 to 1994 and the 1995 population over the period 1995 to 1999 indicated that the Markov model fits well and produces good forecasts under "stable" conditions. The model can also be useful in ascertaining the impact of system changes, such as the widespread introduction of stents in PCI operations in 1995.

Changing risks of stillbirth and neonatal mortality associated with maternal age in Western Australia 1984-2003

There has been a trend over the past two decades in some Western countries for women to delay childbearing, a factor associated with an increased risk of perinatal mortality (stillbirth and neonatal death). While the rates of stillbirth and neonatal mortality have improved in some countries, it has not been established whether maternal age remains a risk factor for perinatal mortality in Australia. The Western Australian Maternal and Child Health Research Database (MCHRDB) was used to examine the effect of maternal age on perinatal death in the periods 1984-93 and 1994-2003 after adjustment for parity and sociodemographic factors. Stillbirths and neonatal deaths were analysed separately. The crude rate of stillbirth has shown little change over the 20 years examined remaining at around 7.5 per 1000 total births, while the rate of neonatal death has decreased steadily from 5.4 per 1000 livebirths in 1984 to 2.0 in 2003. Older maternal age remains a risk factor for stillbirth but the relative risk has declined. After adjustment for parity and sociodemographic factors the relative risk of stillbirth for a woman aged over 40 years (compared with a woman aged 25-29 years) decreased from 2.6 in the period 1984-93, to 1.9 in the period 1994-2003. The increased risk of stillbirth associated with teenage mothers was fully explained by sociodemographic factors in both time periods. No increased risk of neonatal death was evident in the recent period 1994-2003 for teenage or older mothers after adjustment for parity and sociodemographic factors. In spite of some improvements over the past 20 years, women 30 years of age and older continue to be at increased risk of stillbirth. The risk of neonatal death is no longer associated with increased maternal age; however, the small number of cases in the older maternal age groups may be a result of the increased prevalence of antenatal screening and terminations for birth defects.

Can the impact on health of a government policy designed to create more liveable neighbourhoods be evaluated? An overview of the RESIDential Environment Project

There is growing interest in the impact of community design on the health of residents. In 1998, the Western Australian Government began a trial of new subdivision design codes (i.e. Liveable Neighbourhoods Community Design Code) aimed at creating pedestrian-friendly neighbourhoods to increase walking, cycling and public transport use. The trial provided a unique opportunity for a natural experiment to evaluate the impact of a government planning policy on residents. Nevertheless, evaluations of this kind present a number of methodological challenges in obtaining the highest quality evidence possible. This paper describes the RESIDential Environment Project's study design and discusses how various methodological challenges were overcome.

A randomised trial of the short-term effect of a minimal nutrition intervention in general practice

OBJECTIVE

To test the effectiveness of a minimal nutrition intervention to increase dietary intake of folate.

METHOD

Randomised controlled trial in the general practice setting of personalized, face-to-face feedback with educational materials to increase dietary intake of folate.

RESULTS

One hundred and nine intervention and 94 control subjects completed baseline and follow-up assessments within the study period. At baseline (August-October 2004), there were no significant differences in folate intake scores between the intervention and control groups. At the eight-week follow-up, the mean folate intake score in the intervention group was significantly higher than in the control group, indicating that the nutrition intervention significantly increased reported dietary intake of folate.

CONCLUSION

Presenting individual dietary feedback in conjunction with educational materials in the general practice setting is an effective way of changing dietary behaviour.

IMPLICATIONS

The present study suggests a way in which health-related dietary change may be encouraged on a large scale without incurring a large cost.

The Emerging Risk Factors Collaboration: analysis of individual data on lipid, inflammatory and other markers in over 1.1 million participants in 104 prospective studies of cardiovascular diseases

Many long-term prospective studies have reported on associations of cardiovascular diseases with circulating lipid markers and/or inflammatory markers. Studies have not, however, generally been designed to provide reliable estimates under different circumstances and to correct for within-person variability. The Emerging Risk Factors Collaboration has established a central database on over 1.1 million participants from 104 prospective population-based studies, in which subsets have information on lipid and inflammatory markers, other characteristics, as well as major cardiovascular morbidity and cause-specific mortality. Information on repeat measurements on relevant characteristics has been collected in approximately 340,000 participants to enable estimation of and correction for within-person variability. Re-analysis of individual data will yield up to approximately 69,000 incident fatal or nonfatal first ever major cardiovascular outcomes recorded during about 11.7 million person years at risk. The primary analyses will involve age-specific regression models in people without known baseline cardiovascular disease in relation to fatal or nonfatal first ever coronary heart disease outcomes. This initiative will characterize more precisely and in greater detail than has previously been possible the shape and strength of the age- and sex-specific associations of several lipid and inflammatory markers with incident coronary heart disease outcomes (and, secondarily, with other incident cardiovascular outcomes) under a wide range of circumstances. It will, therefore, help to determine to what extent such associations are independent from possible confounding factors and to what extent such markers (separately and in combination) provide incremental predictive value.

Left-handedness and risk of breast cancer

Left-handedness may be an indicator of intrauterine exposure to oestrogens, which may increase the risk of breast cancer. Women (n=1786) from a 1981 health survey in Busselton were followed up using death and cancer registries. Left-handers had higher risk of breast cancer than right-handers and the effect was greater for post-menopausal breast cancer (hazard ratio=2.59, 95% confidence interval 1.11–6.03).

Comparison of Acute Physiology and Chronic Health Evaluation (APACHE) II score with organ failure scores to predict hospital mortality

This study compared the performance of the Acute Physiology and Chronic Health Evaluation (APACHE) II score with two organ failure scores in predicting hospital mortality of critically ill patients. A total of 1311 consecutive adult patients in a tertiary 22-bed multidisciplinary intensive care unit (ICU) in Western Australia were considered. The APACHE II score had a better calibration and discrimination than the Max Sequential Organ Failure Score (Max SOFA) (area under receiver operating characteristic (ROC) curve 0.858 vs 0.829), Admission SOFA (area under ROC 0.858 vs 0.791), and the first day or cumulative 5-day Royal Perth Hospital Intensive Care Unit (RPHICU) organ failure score (area under ROC 0.858 vs 0.822 and 0.819, respectively) in predicting hospital mortality. The APACHE II score predicted hospital mortality of critically ill patients better than the SOFA and RPHICU organ failure scores in our ICU.

A valid semiquantitative food frequency questionnaire to measure fish consumption

OBJECTIVE

To validate a detailed semiquantitative food frequency questionnaire designed to measure habitual fish and seafood consumption.

DESIGN

Cross-sectional validation study using an independent biomarker of fish consumption.

SETTING

Perth metropolitan area, Western Australia.

SUBJECTS

Ninety-one healthy volunteers of both sexes aged 21-75 years.

METHODS

Participants completed the questionnaire and provided a fasting blood sample for erythrocyte membrane omega-3 fatty acid (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) analysis. The questionnaire was then validated by linear regression analysis of EPA and DHA levels on categories of fish and seafood and overall consumption, adjusted for age, sex, smoking status, body mass index (BMI) and alcohol intake.

RESULTS

Regression coefficients were statistically significant for most fish and seafood items with both EPA and DHA. The strongest association was observed between oily fish and EPA, whereas no significant association was observed between lean fish and omega-3 fatty acids. Variation in omega-3 fatty acids was best accounted for by a model containing variables representing different categories of fish and seafood consumption (R (2) 0.484), rather than a single variable representing overall fish and seafood consumption (R (2) 0.313).

CONCLUSIONS

This study confirms that the varying content of omega-3 fatty acids in foods are reflected in omega-3 biomarkers, and that the questionnaire is a valid measure of fish consumption that enables differentiation between cooking and processing methods and oily versus lean fish intake.

Longitudinal study of risk factors for habitual snoring in a general adult population: the Busselton Health Study

BACKGROUND

The aim of this longitudinal study was to identify body size, behavioral, and respiratory risk factors for the development of habitual snoring in a general adult population.

METHODS

The sample for this study comprised 967 adults aged 25 to 74 years who reported not snoring in the 1981 Busselton Health Survey and who also attended the 1994-1995 follow-up survey. Logistic regression was used to identify and quantify the effect of baseline and change risk factors for the development of habitual snoring.

RESULTS

A total of 13% had become habitual snorers by 1994-1995. Male gender (odds ratio [OR], 3.5) and baseline body mass index (OR, 1.4 per 3.4 kg/m(2)) were significant predictors of habitual snoring; after accounting for these variables, no other baseline body size, behavioral, or respiratory/allergy variables were significantly related to the development of habitual snoring. However, change in body mass index over the 14-year follow-up period (OR, 1.55 per 2.3 kg/m(2)), development of asthma (OR, 2.8), and commencement of smoking (OR, 2.2) were additional significant independent risk factors for development of habitual snoring.

CONCLUSIONS

This study has confirmed male gender, obesity, and weight gain as key determinants of habitual snoring, and has indicated that development of asthma and taking up smoking also play a role. Maintaining a healthy weight and not smoking are recommended lifestyle preventive strategies to reduce the risk of sleep-disordered breathing and its sequelae.

A comparison of admission and worst 24-hour Acute Physiology and Chronic Health Evaluation II scores in predicting hospital mortality: a retrospective cohort study

Introduction

The Acute Physiology and Chronic Health Evaluation (APACHE) II score is widely used in the intensive care unit (ICU) as a scoring system for research and clinical audit purposes. Physiological data for calculation of the APACHE II score are derived from the worst values in the first 24 hours after admission to the ICU. The collection of physiological data on admission only is probably logistically easier, and this approach is used by some ICUs. This study compares the performance of APACHE II scores calculated using admission data with those obtained from the worst values in the first 24 hours.

Materials and Methods

This was a retrospective cohort study using prospectively collected data from a tertiary ICU. There were no missing physiological data and follow-up for mortality was available for all patients in the database. The admission and the worst 24-hour physiological variables were used to generate the admission APACHE II score and the worst 24-hour APACHE II score, and the corresponding predicted mortality, respectively.

Results

There were 11,107 noncardiac surgery ICU admissions during 11 years from 1 January 1993 to 31 December 2003. The mean admission and the worst 24-hour APACHE II score were 12.7 and 15.4, and the derived predicted mortality estimates were 15.5% and 19.3%, respectively. The actual hospital mortality was 16.3%. The overall discrimination ability, as measured by the area under the receiver operating characteristic curve, of the admission APACHE II model (83.8%, 95% confidence interval = 82.9–84.7) and the worst 24-hour APACHE II model (84.6%, 95% confidence interval = 83.7–85.5) was not significantly different (P = 1.00).

Conclusion

Substitution of the worst 24-hour physiological variables with the admission physiological variables to calculate the admission APACHE II score maintains the overall discrimination ability of the traditional APACHE II model. The admission APACHE II model represents a potential alternative model to the worst 24-hour APACHE II model in critically ill nontrauma patients.

Data linkage enables evaluation of long-term survival after intensive care

Outcomes of intensive care are important to the patient and for assessment of benefit. Short-term outcomes after critical illness are well described, but less is known about long-term outcomes. This study describes the use of data linkage, combining intensive care unit (ICU) clinical data with administrative morbidity and mortality data, to assess long-term outcomes after treatment in ICU. The hospital-based cohort study was conducted in a 22-bed general ICU in a metropolitan teaching hospital. All patient admissions admitted to ICU from 1 January 1987 to 31 December 2002 were included. The prospective ICU clinical database with patient demographics, ICU diagnoses, severity of illness, daily assessment of organ failures and common daily treatments used was linked using probabilistic methods to the state-wide hospital morbidity and mortality databases to describe long-term survival. There were 26,019 ICU admissions (22,980 patients) with 25,972 records (99.8%) linked to a hospitalization event that included the index ICU admission. Unadjusted survival was 84.7% at 1 year decreasing progressively to 50.7% at 15 years. Age, type of admission, severity of illness (measured by Acute Physiologic and Chronic Health Evaluation (APACHE) II and the presence of organ failure), ICU length of stay, comorbidity (Chronic Health Evaluation and Charlson comorbidity index) and ICU admission diagnosis, were all associated with survival at 1, 3, 5, 10, and 15 year follow-up (P<0.001 at all time points). Linkage of clinical and administrative data provides a feasible method for ascertaining long-term survival after critical illness. Age, admission severity of illness, diagnosis and comorbidity influenced long-term unadjusted survival.

Development of a reliable measure of walking within and outside the local neighborhood: RESIDE's Neighborhood Physical Activity Questionnaire

BACKGROUND

The RESIDential Environment project (RESIDE) is a longitudinal study evaluating the impact of a new residential design code on walking.

OBJECTIVE

To develop a reliable measure of walking--undertaken within and outside the neighborhood--and overall physical activity.

METHODS

A test-retest reliability study was undertaken (n = 82, mean age 39 years). The instrument was based on the International Physical Activity Questionnaire (IPAQ-short version) and Active Australia Survey. It measured usual frequency and duration of (1) recreational- and transport-related walking within and outside the neighborhood and (2) other vigorous and moderate physical activities.

RESULTS

Reliability of recall of whether participants had walked within (k = 0.84) and outside (0.73) the neighborhood was acceptable. Similarly, recall of frequency and duration of transport and recreational-related walking within the neighborhood was excellent (ICC > or = 0.82), as was recall of transport-related walking trips outside the neighborhood (ICC > or = 0.84). Reliability for duration of recreational walking outside the neighborhood was fair to good (ICC = 0.55). The reliability of indices of total physical activity based on MET min/week (ICC = 0.82) and MET min/week dichotomized to 'sufficient' physical activity for health (kappa = 0.67) were both acceptable.

CONCLUSIONS

The Neighborhood Physical Activity Questionnaire (NPAQ) is sufficiently reliable for studies examining environmental correlates of walking within the neighborhood.