Identification of risk factors for hospital admission using multiple-failure survival models: a toolkit for researchers

Slow walking speed and health-related exit from employment among older workers over 5 years of follow-up: evidence from the Health and Employment After Fifty (HEAF) cohort study

INTRODUCTION

With demographic changes, there is increasing demand for individuals and governments to lengthen working lives. Jobs that are very physically demanding are likely to be more difficult to sustain at older ages. If workers at risk of mismatch of demand and capability could be identified early, there would be opportunities for intervention for health or lifestyle and/or re-training or redeployment.

OBJECTIVE

To investigate whether self-reported walking speed (a good measure of function in elderly people) predicted health-related job loss (HRJL) longitudinally over 5 years of follow-up among middle-aged workers.

DESIGN

Data came from the Health and Employment After Fifty (HEAF) prospective cohort study of middle-aged people (aged 50-64 years) in UK.

SETTING

General population survey (sampling frame was 24 General Practice registers).

PARTICIPANTS

The cohort included 8134 people recruited in 2013-2014. For the current analyses, 5217 people who ever worked and completed at least one follow-up questionnaire were eligible.

PRIMARY OUTCOME

Exit from employment mainly or partly for health reasons (HRJL).

RESULTS

At baseline, very slow walking speed was associated with: obesity, physical inactivity, smoking (men), financial hardship, lower educational attainment and not being in professional occupations. In total, 527 people (10%) reported at least one HRJL during follow-up. After adjustment, the HR for HRJL among men with very slow walking-speed was 4.32, 95% CI 2.72 to 6.87 and among women was 4.47, 95% CI 3.04 to 6.57. After further adjustment for 'difficulty coping with physical demands at work', hazards remained doubled in men and women.

CONCLUSIONS

Self-reported walking speed could help identify older workers who are at increased risk of HRJL. This could provide opportunities for intervention through optimising health and lifestyle, restricting physical workload, retraining or redeployment. Early appropriate intervention could enable longer working lives and promote healthier, more equal ageing.

Hospital admissions associated with dehydration in childhood kidney transplantation

BACKGROUND

Paediatric kidney transplant recipients may be at a particular risk of dehydration due to poor kidney concentrating capacity and illness associated with poor fluid intake or losses. In this population, creatinine rise may be more likely with relatively mild dehydration, which may trigger hospital admission. This study describes hospital admissions in the first 12 months after transplantation with diagnosis of graft dysfunction associated with dehydration due to illness or poor fluid intake. We assess risk factors for these admissions.

METHODS

Data was extracted from medical records of patients transplanted in two tertiary children hospitals. Following descriptive analysis, multiple failure regression analyses were used to identify factors associated with admission for acute kidney allograft dysfunction associated with dehydration.

RESULTS

Of 92 children, 42% had at least 1 dehydration admission in the 12 months following transplantation. Almost half of the dehydration admissions were due to poor fluid intake, which accounted for 1/5 of all unplanned hospital admissions. Target fluid intake at first discharge of > 100 ml/kg/day was associated with dehydration admissions of all types (hazard ratio (HR) 2.04 (95% CI 1.13-3.68)). Teen age was associated with poor fluid intake dehydration admissions (HR 4.87 (95% CI 1.19-19.86)), which were more frequent in mid-summer. Use of enteric feeding tube, which correlated with age under 4, associated with contributing illness dehydration admissions (HR 2.18 (95% CI 1.08-4.41)).

CONCLUSIONS

Dehydration admissions in the 12 months following childhood kidney transplantation are common. Highlighted admission risk factors should prompt further study into optimal fluid intake prescription and hydration advice given to children, teenagers, and their carers following kidney transplantation. Use of an enteric feeding tube may not protect patients from admission with dehydration associated with contributing illness. A highger resolution version of the Graphical abstract is available as Supplementary information.

Trends in inequalities in avoidable hospitalisations across the COVID-19 pandemic: a cohort study of 23.5 million people in England

OBJECTIVE

To determine whether periods of disruption were associated with increased 'avoidable' hospital admissions and wider social inequalities in England.

DESIGN

Observational repeated cross-sectional study.

SETTING

England (January 2019 to March 2022).

PARTICIPANTS

With the approval of NHS England we used individual-level electronic health records from OpenSAFELY, which covered ~40% of general practices in England (mean monthly population size 23.5 million people).

PRIMARY AND SECONDARY OUTCOME MEASURES

We estimated crude and directly age-standardised rates for potentially preventable unplanned hospital admissions: ambulatory care sensitive conditions and urgent emergency sensitive conditions. We considered how trends in these outcomes varied by three measures of social and spatial inequality: neighbourhood socioeconomic deprivation, ethnicity and geographical region.

RESULTS

There were large declines in avoidable hospitalisations during the first national lockdown (March to May 2020). Trends increased post-lockdown but never reached 2019 levels. The exception to these trends was for vaccine-preventable ambulatory care sensitive admissions which remained low throughout 2020-2021. While trends were consistent by each measure of inequality, absolute levels of inequalities narrowed across levels of neighbourhood socioeconomic deprivation, Asian ethnicity (compared with white ethnicity) and geographical region (especially in northern regions).

CONCLUSIONS

We found no evidence that periods of healthcare disruption from the COVID-19 pandemic resulted in more avoidable hospitalisations. Falling avoidable hospital admissions has coincided with declining inequalities most strongly by level of deprivation, but also for Asian ethnic groups and northern regions of England.

Severe and common mental disorders and risk of emergency hospital admissions for ambulatory care sensitive conditions among the UK Biobank cohort

BACKGROUND

People with mental disorders have worse physical health compared with the general population, which could be attributable to receiving poorer quality healthcare.

AIMS

To examine the relationship between severe and common mental disorders and risk of emergency hospital admissions for ambulatory care sensitive conditions (ACSCs), and factors associated with increased risk.

METHOD

Baseline data for England (N = 445 814) were taken from UK Biobank, which recruited participants aged 37-73 years during 2006-2010, and linked to hospital admission records up to 31 December 2019. Participants were grouped into those with a history of either schizophrenia, bipolar disorder, depression or anxiety, or no mental disorder. Survival analysis was used to assess the risk of hospital admission for ACSCs among those with mental disorders compared with those without, adjusting for factors in different domains (sociodemographic, socioeconomic, health and biomarkers, health-related behaviours, social isolation and psychological).

RESULTS

People with schizophrenia had the highest (unadjusted) risk of hospital admission for ACSCs compared with those with no mental disorder (hazard ratio 4.40, 95% CI 4.04-4.80). People with bipolar disorder (hazard ratio 2.48, 95% CI 2.28-2.69) and depression or anxiety (hazard ratio 1.76, 95% CI 1.73-1.80) also had higher risk. Associations were more conservative when including all admissions, as opposed to first admissions only. The observed associations persisted after adjusting for a range of factors.

CONCLUSIONS

People with severe mental disorders have the highest risk of preventable hospital admissions. Ensuring people with mental disorders receive adequate ambulatory care is essential to reduce the large health inequalities they experience.

Use of linked patient data to assess the effect of Long-COVID on system-wide healthcare utilisation

Background: Within the relatively early stages of the COVID-19 pandemic, there had been an awareness of the potential longer-term effects of infection (so called Long-COVID) but little was known of the ongoing demands such patients may place on healthcare services. Objective: To investigate whether COVID-19 illness is associated with increased post-acute healthcare utilisation. Method: Using linked data from primary care, secondary care, mental health and community services, activity volumes were compared across the 3 months preceding and proceeding COVID-19 diagnoses for 7,791 individuals, with a distinction made between whether or not patients were hospitalised for treatment. Differences were assessed against those of a control group containing individuals who had not received a COVID-19 diagnosis. All data were sourced from the authors' healthcare system in South West England. Results: For hospitalised COVID-19 cases, a statistically significant increase in non-elective admissions was identified for males and females <65 years. For non-hospitalised cases, statistically significant increases were identified in GP Doctor and Nurse attendances and GP prescriptions (males and females, all ages); Emergency Department attendances (females <65 years); Mental Health contacts (males and females ≥65 years); and Outpatient consultations (males ≥65 years). Conclusion: There is evidence of an association between positive COVID-19 diagnosis and increased post-acute activity within particular healthcare settings. Linked patient-level data provides information that can be useful to understand ongoing healthcare needs resulting from Long-COVID, and support the configuration of Long-COVID pathways of care.

Associations between self-reported healthcare disruption due to covid-19 and avoidable hospital admission: evidence from seven linked longitudinal studies for England

OBJECTIVES

To examine whether there is an association between people who experienced disrupted access to healthcare during the covid-19 pandemic and risk of an avoidable hospital admission.

DESIGN

Observational analysis using evidence from seven linked longitudinal cohort studies for England.

SETTING

Studies linked to electronic health records from NHS Digital from 1 March 2020 to 25 August 2022. Data were accessed using the UK Longitudinal Linkage Collaboration trusted research environment.

PARTICIPANTS

Individual level records for 29 276 people.

MAIN OUTCOME MEASURES

Avoidable hospital admissions defined as emergency hospital admissions for ambulatory care sensitive and emergency urgent care sensitive conditions.

RESULTS

9742 participants (weighted percentage 35%, adjusted for sample structure of longitudinal cohorts) self-reported some form of disrupted access to healthcare during the covid-19 pandemic. People with disrupted access were at increased risk of any (odds ratio 1.80, 95% confidence interval 1.39 to 2.34), acute (2.01, 1.39 to 2.92), and chronic (1.80, 1.31 to 2.48) ambulatory care sensitive hospital admissions. For people who experienced disrupted access to appointments (eg, visiting their doctor or an outpatient department) and procedures (eg, surgery, cancer treatment), positive associations were found with measures of avoidable hospital admissions.

CONCLUSIONS

Evidence from linked individual level data shows that people whose access to healthcare was disrupted were more likely to have a potentially preventable hospital admission. The findings highlight the need to increase healthcare investment to tackle the short and long term implications of the pandemic, and to protect treatments and procedures during future pandemics.

Recurrent risk of hospitalization among older people with problematic alcohol use: a multiple failure-time analysis with a discontinuous risk model

BACKGROUND AND AIMS

Older people with problematic alcohol use vary in psychosocial functioning, age of onset for problem drinking and use of other drugs. The study measured the differential risks of all-cause, alcohol-, polydrug- and psychiatric-related repeated hospitalizations among older people with problematic alcohol use.

DESIGN

A linked register-based cohort study with discontinuous multiple-failure (time-to-repeated-event) data. Hospitalization and mortality were considered as failure.

SETTING

Sweden, March 2003-November 2017, using data from the Addiction Severity Index (ASI) register linked to National Inpatient Register and the Swedish cause of death register.

PARTICIPANTS

Participants aged 50 years and older (n = 1741; 28.2% women), with one or more alcohol problem days in the 30 days before an ASI assessment.

MEASUREMENTS

Five mutually exclusive latent classes of problematic alcohol use, identified with 11 ASI items, were the independent variables: 'late onset with fewer consequences (LO:FC; reference group)'; 'early onset/prevalent multi-dimensional problems (EO:MD)'; 'late onset with co-occurring anxiety and depression (LO:AD)'; 'early onset with co-occurring psychiatric problems (EO:PP)'; and 'early onset with major alcohol problem (EO:AP)'. Covariates included socio-demographic characteristics, previous hospitalization and Elixhauser comorbidity index. Outcome measurements included recurrent hospitalization and/or mortality due to: (a) all-cause, (b) alcohol-related disorders and diseases (c) polydrug use and (d) other psychiatric disorders.

FINDINGS

During the study period, more than 75% were hospitalized at least once or died. 57.3% were hospitalized with alcohol-related, 8.5% with polydrug use and 18.5% with psychiatric-related diagnoses. Compared with LO:FC, EO:PP had higher risk for all-cause [adjusted hazard ratio (aHR) = 1.27, 95% confidence interval (CI) = 1.02-1.59] and alcohol-related (aHR = 1.34, 95% CI = 1.02-1.75) hospitalizations. Adjusted risks for polydrug-related hospitalization were 2.55, 95% CI = 1.04-6.27 for EO:MD and 2.62, 95% CI = 1.07-6.40 for EO:PP. Adjusted risk for psychiatric-related hospitalization was higher for LO:AD (aHR = 1.78, 95% CI = 1.16-2.73 and EO:PP (aHR = 2.03, 95% CI = 1.22-3.38).

CONCLUSIONS

Older addiction service users in Sweden have varying risks of hospitalization due to alcohol use, polydrug use and psychiatric disorders. Older people with problematic alcohol use who have multiple needs and are assessed in social services may benefit from earlier interventions with an integrated focus on substance use and mental health.

Prognostic indicators for in-hospital mortality in COPD with acute exacerbation in Thailand: a retrospective cohort study

Background

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is a common and deteriorating event leading to in-hospital morbidity and mortality. Identification of predictors for in-hospital mortality of AECOPD patients could aid clinicians in identifying patients with a higher risk of death during their hospitalisation.

Objective

To explore potential prognostic indicators associated with in-hospital mortality of AECOPD patients.

Setting

General medical ward and medical intensive care unit of a university-affiliated tertiary care centre.

Methods

A prognostic factor research was conducted with a retrospective cohort design. All admission records of AECOPD patients between October 2015 and September 2016 were retrieved. Stratified Cox’s regression was used for the primary analysis.

Results

A total of 516 admission records of 358 AECOPD patients were included in this study. The in-hospital mortality rate of the cohort was 1.9 per 100 person-day. From stratified Cox’s proportional hazard regression, the predictors of in-hospital mortality were aged 80 years or more (HR=2.16, 95% CI: 1.26 to 3.72, p=0.005), respiratory failure on admission (HR=2.50, 95% CI: 1.12 to 5.57, p=0.025), body temperature more than 38°C (HR=2.97, 95% CI: 1.61 to 5.51, p=0.001), mean arterial pressure lower than 65 mm Hg (HR=4.01, 95% CI: 1.88 to 8.60, p<0.001), white blood cell count more than 15 x 10⁹/L (HR=3.51, 95% CI: 1.90 to 6.48, p<0.001) and serum creatinine more than 1.5 mg/dL (HR=2.08, 95% CI: 1.17 to 3.70, p=0.013).

Conclusion

Six independent prognostic indicators for in-hospital mortality of AECOPD patients were identified. All of the parameters were readily available in routine practice and can be used as an aid for risk stratification of AECOPD patients.

Maternal depression and childhood injury risk: A population-based cohort study in Denmark

AIMS

To assess the association between different stages of maternal depression and injury risk in offspring aged 0-10 years.

METHODS

Population-based cohort study of all live-born children in Denmark from 1 January 1997 until 31 December 2013 (n = 1,064,387). Main outcome measure was emergency department contacts with a main diagnosis of injury coded as DS00-DT98 (chapter XIX) according to the ICD-10. All information was obtained from Danish national registries.

RESULTS

Maternal depression was associated with higher injury hazard in the offspring throughout childhood compared to offspring of mothers with no history of depression. The strongest association was seen for the first year of life. First-time maternal depression was most strongly associated with injury in the child, especially in the first year of life (aHR = 1.70, 95% CI: 1.48-1.96). Children of mothers with relapse depression had 1.57 higher hazard of injury in the first year of life (aHR: 1.57, 95% CI: 1.44-1.70). Children of mothers with previously treated depression (postdepression) had 1.13 higher hazard of injury in the first year of life (aHR: 1.13, 95% CI: 1.09-1.17). Continuous treatment for depression was associated with a nonsignificant higher hazard of injuries in the first year of life (aHR: 1.06, 95% CI: 0.91-1.23).

CONCLUSIONS

Maternal depression was associated with higher injury risk in the offspring, particularly in early childhood. The association persisted in children of mothers with relapse depression. Our results suggest that children of mothers with depression are vulnerable several years after depression onset and treatment cessation.

Demographic and socioeconomic patterns in the risk of alcohol-related hospital admission in children and young adults with childhood onset type-1 diabetes from a record-linked longitudinal population cohort study in Wales

BACKGROUND

Little is known about alcohol-related harm in children and young adults with type 1 diabetes (T1D). Education on managing alcohol intake is provided to teenagers with T1D in paediatric clinics in Wales, but its effectiveness is unknown. We compared the patterns in risk of alcohol-related hospital admissions (ARHA) between individuals with and without childhood-onset T1D.

METHODS

We extracted data for 1 791 577 individuals born during 1979 to 2014 with a general practitioner registration in Wales, and record-linked the demographic data to ARHA between 1998 and June 2016 within the Secure Anonymised Information Linkage Databank (SAIL). Linkage to a national T1D register (Brecon Cohort) identified 3575 children diagnosed aged <15 years since 1995. We estimated hazard ratios (HRs) with 95% confidence intervals (95% CIs) for the risk of ARHA using recurrent-event models, including interaction terms.

RESULTS

Individuals with T1D had a higher riskof ARHA (HR: 1.78; 95% CI: 1.60-1.98), adjusted for age group, sex, and deprivation. The risk in people with diabetes was highest aged 14 to 17 years, around three times higher than the peak in non-T1D aged 18 to 22. Females with diabetes had a lower risk generally. The association between deprivation and ARHA was weaker in the T1D group.

CONCLUSION

Young people with T1D had increased risks of ARHA, particularly at school age, and smaller socioeconomic inequalities in ARHA. A review of interventions to reduce alcohol-related harm in T1D is needed, perhaps including modification of current education and guidance for teenagers on managing alcohol consumption and reviewing criteria for hospital admission.

Work participation and risk factors for health-related job loss among older workers in the Health and Employment after Fifty (HEAF) study: Evidence from a 2-year follow-up period

INTRODUCTION

Rapidly increasing population old age dependency ratios create a growing economic imperative for people to work to older ages. However, rates of older worker employment are only increasing slowly. Amongst a cohort of contemporary older workers, we investigated risk factors for health-related job loss (HRJL) over 2 years of follow-up.

METHODS

HEAF is a population based cohort study of adults in England (aged 50-64 years at baseline) who provided information about socio-demographic characteristics, lifestyle, and work at baseline and annual follow-ups. Exits from paid work were mapped and risk factors for HRJL explored in a multiple-record survival dataset by Cox proportional hazards models.

RESULTS

2475 (75%) men and 2668 (66%) women were employed; 115 (4.6%) men and 182 (6.8%) women reported HRJL. Employment as road transport drivers/in vehicle trades (men), or as teaching/education/nursing/midwifery professionals or in caring personal services (women), was more frequent among people exiting work for health-related versus non-health-related reasons. Principal socio-demographic and lifestyle risk factors for HRJL were: struggling financially (men and women); low physical activity (men); being overweight or obese, and current smoking (women). Mutually adjusted work-related risk factors for HRJL were job dissatisfaction, and not coping with the physical (hazard ratio [95% confidence interval]: men 5.34[3.40,8.39]; women 3.73[2.48,5.60]) or mental demands (women only, 2.02[1.38,2.96]) of work.

CONCLUSIONS

Employment characteristics of contemporary older workers differ by sex. Job satisfaction and perceived ability to cope with the physical and mental demands of work are key determinants of HRJL which employers could potentially influence to enable work to older ages.

Obesity and risk of infections: results from men and women in the Swedish National March Cohort

BACKGROUND

Previous studies have shown an association between body mass index (BMI) and infections, but the literature on type-specific community acquired infections is still limited.

METHODS

We included 39 163 Swedish adults who completed a questionnaire in September 1997 and were followed through record-linkages until December 2016. Information on BMI was self-reported and infections were identified from the Swedish National Patient Register using International Classification of Diseases (ICD), Tenth Revision (ICD-10) codes. We fitted multivariable Cox proportional hazards models for time-to-first-event analysis, and we used extensions of the standard Cox model when repeated events were included.

RESULTS

During a 19-year follow-up 32% of the subjects had at least one infection requiring health care contact, leading to a total of 27 675 events. We found an increased incidence of any infection in obese women [hazard ratio (HR) = 1.22; 95% confidence interval (CI) = 1.12; 1.33] and obese men (HR = 1.25; 95% CI = 1.09; 1.43) compared with normal weight subjects. For specific infections, higher incidences were observed for skin infections in both genders (HR = 1.76; 95% CI = 1.47; 2.12 for obese females and HR = 1.74; 95% CI = 1.33; 2.28 for obese males) and gastrointestinal tract infections (HR = 1.44; 95% CI = 1.19; 1.75), urinary tract infections (HR = 1.30; 95% CI = 1.08; 1.55) and sepsis (HR = 2.09; 95% CI = 1.46; 2.99) in obese females. When accounting for repeated events, estimates similar to the aforementioned ones were found.

CONCLUSIONS

Obesity was associated with an increased risk of infections in both genders. Results from multiple-failure survival analysis were consistent with those from classic Cox models.

Cumulative burden of subsequent neoplasms, cardiovascular and respiratory morbidity in young people surviving cancer

BACKGROUND

Long-term childhood and young adult cancer survivors are at increased risk of the late effects of multiple chronic conditions. In this study we estimate the cumulative burden of subsequent malignant neoplasms (SMN), cardiovascular and respiratory hospitalisations in long-term survivors of childhood and young adult cancers and associated treatment risks.

METHODS

Five-year survivors of cancer diagnosed aged 0-29 years between 1992-2009 in Yorkshire, UK were included. The cumulative count of all hospital admissions (including readmissions) for cardiovascular and respiratory conditions and all SMNs diagnosed up to 2015 was calculated, with death as a competing risk. Associations between treatment exposures and cumulative burden were investigated using multiple-failure time survival models.

RESULTS

A total of 3464 5-year survivors were included with a median follow-up of 8.2 years (IQR 4-13 years). Ten-years post diagnosis, the cumulative incidence for a respiratory admission was 6.0 % (95 %CI 5.2-6.9), a cardiovascular admission was 2.0 % (95 %CI 1.5-2.5), and SMN was 1.0 % (95 % CI 0.7-1.4) with an average of 13 events per 100 survivors observed (95 %CI 11-15). The risk of experiencing multiple events was higher for those treated with chemotherapy drugs with known lung toxicity (HR = 1.35, 95 %CI 1.09-1.68).

DISCUSSION

Survivors of childhood and young adult cancer experience a high burden of morbidity due to respiratory, cardiovascular diseases and SMNs up to 20-years post-diagnosis. Statistical methods that capture multiple morbidities and recurrent events are important when quantifying the burden of late effects in young cancer survivors.

Impact of type 2 diabetes on hospitalization and mortality in people with malignancy

AIM

To compare the characteristics of and outcomes for people with malignancies with and without a co-diagnosis of diabetes.

METHODS

Emergency department and hospital discharge data from a single centre for the period between 1 January 2015 and 31 December 2017 were used to identify people with a diagnosis of a malignancy and diabetes. Multivariate Cox regression models were used to estimate the effect of diabetes on all-cause mortality. A truncated negative binomial regression model was used to assess the impact of diabetes on length of hospital inpatient stay. Prentice-Williams-Peterson total time models were used to assess the effect of diabetes on number of emergency department re-presentations and inpatient re-admissions.

RESULTS

Of 7004 people identified with malignancies, 1195 (17.1%) were also diagnosed with diabetes. A diagnosis of diabetes was associated with a greater number of inpatient re-admissions [adjusted hazard ratio 1.13 (95% CI 1.03, 1.24)], a greater number of emergency department re-presentations [adjusted hazard ratio 1.13 (95% CI 1.05, 1.22)] and longer length of stay [adjusted incidence rate ratio 1.14 (95% CI 1.04, 1.25)]. A co-diagnosis of diabetes was also associated with a 48% increased risk of all-cause mortality [adjusted hazard ratio 1.48 (95% CI 1.22-1.76)].

CONCLUSIONS

People with malignancies and diabetes had significantly more emergency department presentations, more inpatient admissions, longer length of hospital stay and higher rates of all-cause mortality compared to people with a malignancy without diabetes.

The Hertfordshire Cohort Study: an overview

The Hertfordshire Cohort Study is a nationally unique study of men and women born in the English county of Hertfordshire in the early part of the 20 ^th century. Records that detail their health in infancy and childhood have been preserved, their sociodemographic, lifestyle, medical and biological attributes have been characterised in later life, and routinely collected data on their hospital use and mortality have been acquired. This paper provides an overview of the study since its inception in the 1980s, including its methods, findings, and plans for its future.

A Bayesian two-stage regression approach of analysing longitudinal outcomes with endogeneity and incompleteness

Abstract:

Two-stage regression methods are typically used for handling endogeneity in the simultaneous equations models in economics and other social sciences. However, the problem is challenging in the presence of incomplete response and/or incomplete endogenous covariate(s). We propose a Bayesian approach for the joint modelling of incomplete longitudinal continuous response and an incomplete count endogenous covariate, where the incompleteness is caused by the censorship through a selection mechanism. We define latent continuous variables which are left-censored at zero and develop a Gibbs sampling algorithm for the simultaneous estimation of the model parameters. We consider partially varying coefficients regression models containing covariates with fixed and time-varying effects on the response. Our work is motivated by a sample dataset from the Health and Retirement Study (HRS) for modelling the out-of-pocket medical cost, where the number of hospital admissions is considered as an endogenous covariate. Our analysis addresses some of the previously unanswered questions on the physical and financial health of the older population based on HRS data. Simulation studies are performed for assessing the usefulness of the proposed method compared to its competitors.

Understanding poor health behaviours as predictors of different types of hospital admission in older people: findings from the Hertfordshire Cohort Study

BACKGROUND

Rates of hospital admission are increasing, particularly among older people. Poor health behaviours cluster but their combined impact on risk of hospital admission among older people in the UK is unknown.

METHODS

2997 community-dwelling men and women (aged 59-73) participated in the Hertfordshire Cohort Study (HCS). We scored (from 0 to 4) number of poor health behaviours engaged in at baseline (1998-2004) out of: current smoking, high weekly alcohol, low customary physical activity and poor diet. We linked HCS with Hospital Episode Statistics and mortality data to 31/03/2010 and analysed associations between the score and risk of different types of hospital admission: any; elective; emergency; long stay (>7 days); 30-day readmission (any, or emergency).

RESULTS

32%, 40%, 20% and 7% of men engaged in 0, 1, 2 and 3/4 poor health behaviours; corresponding percentages for women 51%, 38%, 9%, 2%. 75% of men (69% women) experienced at least one hospital admission. Among men and women, increased number of poor health behaviours was strongly associated (p<0.01) with greater risk of long stay and emergency admissions, and 30-day emergency readmissions. Hazard ratios (HRs) for emergency admission for 3/4 poor health behaviours in comparison with none were: men, 1.37 (95% CI 1.11 to 1.69); women, 1.84 (95% CI 1.22 to 2.77). Associations were unaltered by adjustment for age, body mass index and comorbidity.

CONCLUSIONS

Clustered poor health behaviours are associated with increased risk of hospital admission among older people in the UK. Lifecourse interventions to reduce number of poor health behaviours could have substantial beneficial impact on health and use of healthcare in later life.