Biomedical subjects

Obioha C Ukoumunne

Publications and source records attributed to Obioha C Ukoumunne.

16 recordsLinked to original sources

PubMed2007

A simulation study of odds ratio estimation for binary outcomes from cluster randomized trials.

We used simulation to compare accuracy of estimation and confidence interval coverage of several methods for analysing binary outcomes from cluster randomized trials. The following methods were used to estimate the population-averaged intervention effect on the log-odds scale: marginal logistic regression models using generalized estimating equations with information sandwich estimates of standard error (GEE); unweighted cluster-level mean difference (CL/U); weighted cluster-level mean difference (CL/W) and cluster-level random effects linear regression (CL/RE). Methods were compared across trials simulated with different numbers of clusters per trial arm, numbers of subjects per cluster, intraclass correlation coefficients (rho), and intervention versus control arm proportions. Two thousand data sets were generated for each combination of design parameter values. The results showed that the GEE method has generally acceptable properties, including close to nominal levels of confidence interval coverage, when a simple adjustment is made for data with relatively few clusters. CL/U and CL/W have good properties for trials where the number of subjects per cluster is sufficiently large and rho is sufficiently small. CL/RE also has good properties in this situation provided a t-distribution multiplier is used for confidence interval calculation in studies with small numbers of clusters. For studies where the number of subjects per cluster is small and rho is large all cluster-level methods may perform poorly for studies with between 10 and 50 clusters per trial arm.

Algorithms↗

PubMed2007

Adverse associations of sleep problems in Australian preschoolers: national population study.

OBJECTIVE: In contrast to school-aged children, the impact of sleep problems in preschool-aged children is not well documented. We aimed to determine relationships between preschool-aged child sleep problems and child behavior; health-related quality of life; verbal, preliteracy, and early numeracy skills; diagnosis of attention-deficit/hyperactivity disorder; and injury. PARTICIPANTS AND METHODS: Participants included families (n = 4983) participating in the first wave of the Longitudinal Study of Australian Children, a nationally representative study of Australian children aged 4 to 5 years surveyed from March to November 2004. Measures consisted of a primary caregiver's report of whether their child had a sleep problem (none versus mild versus moderate/severe); specific sleep patterns occurring > or = 4 nights per week; health-related quality of life (by using the Pediatric Quality of Life Inventory 4.0); behavior (by using the Strengths and Difficulties Questionnaire) and parent-reported diagnosis of attention-deficit/hyperactivity disorder; and injury requiring medical attention in the past 12 months. Tests of receptive vocabulary and preliteracy/numeracy skills (by using the Who Am I? developmental assessment and the adapted Peabody Picture Vocabulary Test, 3rd Edition) were directly administered to each child. RESULTS: Sleep problems were common, and compared with children without sleep problems, children with sleep problems had poorer child health-related quality of life, more behavior problems, and higher rates of attention-deficit/hyperactivity disorder. Difficulty going to sleep and morning tiredness had greater adverse associations than snoring or night waking. CONCLUSIONS: Given that sleep problems are very common, the adverse outcomes shown here could affect the transition to school for a very large number of preschoolers.

Attention Deficit Disorder with Hyperactivity↗

PubMed2006

Improving infant sleep and maternal mental health: a cluster randomised trial.

OBJECTIVES: To determine whether a community-delivered intervention targeting infant sleep problems improves infant sleep and maternal well-being and to report the costs of this approach to the healthcare system. DESIGN: Cluster randomised trial. SETTING: 49 Maternal and Child Health (MCH) centres (clusters) in Melbourne, Australia. PARTICIPANTS: 328 mothers reporting an infant sleep problem at 7 months recruited during October-November 2003. INTERVENTION: Behavioural strategies delivered over individual structured MCH consultations versus usual care. MAIN OUTCOME MEASURES: Maternal report of infant sleep problem, depression symptoms (Edinburgh Postnatal Depression Scale (EPDS)), and SF-12 mental and physical health scores when infants were 10 and 12 months old. Costs included MCH sleep consultations, other healthcare services and intervention costs. RESULTS: Prevalence of infant sleep problems was lower in the intervention than control group at 10 months (56% vs 68%; adjusted OR 0.58 (95% CI: 0.36 to 0.94)) and 12 months (39% vs 55%; adjusted OR 0.50 (0.31 to 0.80)). EPDS scores indicated less depression at 10 months (adjusted mean difference -1.4 (-2.3 to -0.4) and 12 months (-1.7 (-2.6 to -0.7)). SF-12 mental health scores indicated better health at 10 months (adjusted mean difference 3.7 (1.5 to 5.8)) and 12 months (3.9 (1.8 to 6.1)). Total mean costs including intervention design, delivery and use of non-MCH nurse services were 96.93 pounds sterling and 116.79 pounds sterling per intervention and control family, respectively. CONCLUSIONS: Implementing this sleep intervention may lead to health gains for infants and mothers and resource savings for the healthcare system. TRIAL REGISTRATION: Current Controlled Trial Registry, number ISRCTN48752250 [controlled-trials.com] (registered November 2004).

Australia↗

PubMed2006

Growth of infant communication between 8 and 12 months: a population study.

AIM: To describe changes in infant prelinguistic communication skills between 8 and 12 months, and identify factors associated with those skills. METHODS DESIGN: Parent questionnaire data for a prospective population-based cohort of infants in metropolitan Melbourne, Australia. PARTICIPANTS: 1911 infants born November 2002-August 2003. OUTCOME: Infant communication (Communication and Symbolic Behaviour Scales (CSBS)) at 8 and 12 months. Potential risk factors: sex; prematurity; multiple birth; sociodemographic indicators; maternal mental health, vocabulary and education; non-English speaking background; and family history of speech-language difficulties. Linear regression models were fitted to total standardised CSBS scores at 8 and 12 months. RESULTS: Social communication, especially the use of gesture, developed rapidly from 8 to 12 months. Female sex, twin birth, and family history were strongly associated with CSBS scores. The combined model accounted for 5% and 6% of the total variation at 8 and 12 months, respectively. CSBS score at 8 months strongly predicted CSBS score at 12 months (coefficient = 0.56, partial R(2) = 37.0). CONCLUSIONS: There is a dramatic increase in communication skills between 8 and 12 months, particularly the development of gesture, which (as in previous studies) predates and predicts future language development. Risk factors explained little variation in early communication trajectories and therefore, based on our findings, this developmental course is more likely to be biologically predetermined. Rather than focusing on risk factors, we suggest that language promotion activities in otherwise healthy young infants should either be universal or, if targeted, be based on the level of communication skills displayed.

Australia↗

PubMed2006

Slight/mild sensorineural hearing loss in children.

OBJECTIVE: The goal was to determine the prevalence and effects of slight/mild bilateral sensorineural hearing loss among children in elementary school. METHODS: A cross-sectional, cluster-sample survey of 6581 children (response: 85%; grade 1: n = 3367; grade 5: n = 3214) in 89 schools in Melbourne, Australia, was performed. Slight/mild bilateral sensorineural hearing loss was defined as a low-frequency pure-tone average across 0.5, 1, and 2 kHz and/or a high-frequency pure-tone average across 3, 4, and 6 kHz of 16 to 40 dB hearing level in the better ear, with air/bone-conduction gaps of < 10 dB. Parents reported children's health-related quality of life and behavior. Each child with slight/mild bilateral sensorineural hearing loss, matched to 2 normally hearing children (low-frequency pure-tone average and high-frequency pure-tone average of < or = 15 dB hearing level in both ears), completed standardized assessments. Whole-sample comparisons were adjusted for type of school, grade level, and gender, and matched-sample comparisons were adjusted for nonverbal IQ scores. RESULTS: Fifty-five children (0.88%) had slight/mild bilateral sensorineural hearing loss. Children with and without sensorineural hearing loss scored similarly in language (mean: 97.2 vs 99.7), reading (101.1 vs 102.8), behavior (8.4 vs 7.0), and parent- and child-reported child health-related quality of life (77.6 vs 80.0 and 76.1 vs 77.0, respectively), but phonologic short-term memory was poorer (91.0 vs 102.8) in the sensorineural hearing loss group. CONCLUSIONS: The prevalence of slight/mild bilateral sensorineural hearing loss was lower than reported in previous studies. There was no strong evidence that slight/mild bilateral sensorineural hearing loss affects adversely language, reading, behavior, or health-related quality of life in children who are otherwise healthy and of normal intelligence.

Child↗

PubMed2005

Intensive case management for severe psychotic illness: is there a general benefit for patients with complex needs? A secondary analysis of the UK700 trial data.

The UK700 trial failed to demonstrate an overall benefit of intensive case management (ICM) in patients with severe psychotic illness. This does not discount a benefit for particular subgroups, and evidence of a benefit of ICM for patients of borderline intelligence has been presented. The aim of this study is to investigate whether this effect is part of a general benefit for patients with severe psychosis complicated by additional needs. In the UK700 trial patients with severe psychosis were randomly allocated to ICM or standard case management. For each patient group with complex needs the effect of ICM is compared with that in the rest of the study cohort. Outcome measures are days spent in psychiatric hospital and the admission and discharge rates. ICM may be of benefit to patients with severe psychosis complicated by borderline intelligence or depression, but may cause patients using illicit drugs to spend more time in hospital. There was no convincing evidence of an effect of ICM in a further seven patient groups. ICM is not of general benefit to patients with severe psychosis complicated by additional needs. The benefit of ICM for patients with borderline intelligence is an isolated effect which should be interpreted cautiously until further data are available.

Critical Care↗

PubMed2004

Availability and structure of primary medical care services and population health and health care indicators in England.

BACKGROUND: It has been proposed that greater availability of primary medical care practitioners (GPs) contributes to better population health. We evaluated whether measures of the supply and structure of primary medical services are associated with health and health care indicators after adjusting for confounding. METHODS: Data for the supply and structure of primary medical services and the characteristics of registered patients were analysed for 99 health authorities in England in 1999. Health and health care indicators as dependent variables included standardised mortality ratios (SMR), standardised hospital admission rates, and conceptions under the age of 18 years. Linear regression analyses were adjusted for Townsend score, proportion of ethnic minorities and proportion of social class IV/ V. RESULTS: Higher proportions of registered rural patients and patients >/= 75 years were associated with lower Townsend deprivation scores, with larger partnership sizes and with better health outcomes. A unit increase in partnership size was associated with a 4.2 (95% confidence interval 1.7 to 6.7) unit decrease in SMR for all-cause mortality at 15-64 years (P = 0.001). A 10% increase in single-handed practices was associated with a 1.5 (0.2 to 2.9) unit increase in SMR (P = 0.027). After additional adjustment for percent of rural and elderly patients, partnership size and proportion of single-handed practices, GP supply was not associated with SMR (-2.8, -6.9 to 1.3, P = 0.183). CONCLUSIONS: After adjusting for confounding with health needs of populations, mortality is weakly associated with the degree of organisation of practices as represented by the partnership size but not with the supply of GPs.

Adolescent↗

PubMed2004

Patterns of intra-cluster correlation from primary care research to inform study design and analysis.

OBJECTIVE: To provide information concerning the magnitude of the intraclass correlation coefficient (ICC) for cluster-based studies set in primary care. STUDY DESIGN AND SETTING: Reanalysis of data from 31 cluster-based studies in primary care to estimate intraclass correlation coefficients from random effects models using maximum likelihood estimation. RESULTS: ICCs were estimated for 1,039 variables. The median ICC was 0.010 (interquartile range [IQR] 0 to 0.032, range 0 to 0.840). After adjusting for individual- and cluster-level characteristics, the median ICC was 0.005 (IQR 0 to 0.021). A given measure showed widely varying ICC estimates in different datasets. In six datasets, the ICCs for SF-36 physical functioning scale ranged from 0.001 to 0.055 and for SF-36 general health from 0 to 0.072. In four datasets, the ICC for systolic blood pressure ranged from 0 to 0.052 and for diastolic blood pressure from 0 to 0.108. CONCLUSION: The precise magnitude of between-cluster variation for a given measure can rarely be estimated in advance. Studies should be designed with reference to the overall distribution of ICCs and with attention to features that increase efficiency.

Cluster Analysis↗

PubMed2004

History of deliberate self-harm and its association with mood fluctuation.

BACKGROUND: It is known that mental illness is associated with increased suicide risk. It has been postulated that suicidality may be an independent clinical phenomenon and we investigate whether variability of mood may be a mediator of this. METHODS: Fifty-three psychiatric inpatients were assessed on the Montgomery-Asberg depression rating scale, once weekly, over a 4-week period. The SCID II was administered to diagnose co-morbid personality disorder. Hostility was measured with the Hostility and Direction of Hostility questionnaire. A Fluctuation Index score was calculated to measure variability of mood. RESULTS: Unadjusted analyses suggested that patients with a history of deliberate self-harm showed greater variability in mood as measured by the fluctuation index (mean difference=13.4; 95% CI=4.3 to 22.6; P=0.005) though this relationship was no longer significant at the 5% level after adjustment (mean difference=13.4; 95% CI=-2.0 to 28.8; P=0.09). LIMITATIONS: There was a high initial dropout rate from the study and a small sample size. A prospective study would have more power in determining the effect of mood fluctuations. CONCLUSIONS: Mood fluctuation may be a useful indicator of risk of deliberate self-harm and attempted suicide.

Adolescent↗

PubMed2004

Promoting patient participation in consultations: a randomised controlled trial to evaluate the effectiveness of three patient-focused interventions.

The aim of this experimental study was to evaluate the effectiveness of three patient-focused interventions designed to increase patient question asking in clinical consultations. Patients were randomly allocated to one of five conditions to receive either one of three interventions or to serve as an attention control group or a control group. The primary outcome measure was question asking by the patient of their physician. Participants in the intervention groups did not ask more questions than participants in the control groups. Immediately after the consultation participants in the intervention groups had higher levels of self-efficacy in asking questions. Three months after the index visit patients in the intervention groups were significantly more likely to be satisfied to some degree than patients in the control group. There was no difference in diabetic control. These results suggest that simple brief patient-focused interventions do not change patient behaviour in medical outpatient consultations.

Adolescent↗

PubMed2004

Life events and survival in dementia: a 5-year follow-up study.

OBJECTIVES: To examine the relationship between life events and survival for people with dementia. To investigate whether this relationship differs from that for people without dementia. To identify which psychiatric and social factors are associated with survival in people with dementia. METHOD: A prospective cohort study with external controls. One hundred and sixteen people with dementia and 50 fit, elderly controls were assessed for life events over a 6-month period. They were followed-up at 5 years and data collected on length of survival. RESULTS: There was an association between two or more severe life events and reduced survival. This association appeared stronger for controls than people with dementia although the interaction was not significant (p = 0.052). The only psychiatric or social factor associated with poor survival in dementia was depression. Other factors associated with reduced survival in the dementia group were male sex, older age, poor physical health, later age of onset and a poorer level of functioning. CONCLUSIONS: This study provides some evidence that having two or more stressful and negative life events may reduce survival in older people with and without dementia. If replicated, this finding will have implications for our understanding of the clinical course of dementia.

Aged↗

PubMed2004

Lessons for cluster randomized trials in the twenty-first century: a systematic review of trials in primary care.

BACKGROUND: Evidence suggests that cluster randomized trials are often poorly designed and analysed. There is little recent research on the methodologic quality of cluster randomized trials and none focuses on primary health care where these trials are increasingly common. METHODS: We conducted a systematic review of recent cluster randomized trials in primary health care, searching the Cochrane Controlled Trials Register. We also searched for unpublished trials in conference proceedings, and the UK National Research Register. We assess methodologic quality using a checklist, articulate problems facing investigators conducting these trials, and examine the extent to which carrying out a cluster randomized trial (as opposed to an individually randomized trial) in primary care may reduce power. RESULTS: We found 367 trial reports. Many trials were reported more than once. We characterize 152 independent cluster randomized trials in primary health care published between 1997 and 2000, and briefly describe 47 trials unpublished at December 2000. The quality of design and analysis was variable. Of published trials reporting sample size calculations 20% accounted for clustering in these calculations, 59% of published trials accounted for clustering in analyses. Unpublished trials were more recent and of higher quality. Reporting quality was better in journals reporting more cluster randomized trials. Many trial investigators reported problems with adherence to protocol, recruitment and type of intervention. CONCLUSIONS: Methodologic quality of cluster randomized trials in primary health care is variable and reporting needs improvement. The use of cluster randomization should be indicated in the title or abstract so these kinds of trials are easier to identify. Communicating appropriate methodology to health care researchers continues to be a challenge. Cluster randomized trials should always be piloted and information from pilots and unsuccessful trials shared more widely.

Cluster Analysis↗

PubMed2003

Non-parametric bootstrap confidence intervals for the intraclass correlation coefficient.

The intraclass correlation coefficient rho plays a key role in the design of cluster randomized trials. Estimates of rho obtained from previous cluster trials and used to inform sample size calculation in planned trials may be imprecise due to the typically small numbers of clusters in such studies. It may be useful to quantify this imprecision. This study used simulation to compare different methods for assigning bootstrap confidence intervals to rho for continuous outcomes from a balanced design. Data were simulated for combinations of numbers of clusters (10, 30, 50), intraclass correlation coefficients (0.001, 0.01, 0.05, 0.3) and outcome distributions (normal, non-normal continuous). The basic, bootstrap-t, percentile, bias corrected and bias corrected accelerated bootstrap intervals were compared with new methods using the basic and bootstrap-t intervals applied to a variance stabilizing transformation of rho. The standard bootstrap methods provided coverage levels for 95 per cent intervals that were markedly lower than the nominal level for data sets with only 10 clusters, and only provided close to 95 per cent coverage when there were 50 clusters. Application of the bootstrap-t method to the variance stabilizing transformation of rho improved upon the performance of the standard bootstrap methods, providing close to nominal coverage.

Cluster Analysis↗

PubMed2003

Service variation in baseline variables and prediction of risk in a randomised controlled trial of psychological treatment in repeated parasuicide: the POPMACT Study.

The treatment protocol and baseline characteristics of 480 subjects with a history of repeated parasuicide recruited in five centres to a randomised therapeutic trial of manual assisted cognitive-behaviour therapy (MACT) and treatment as usual (TAU) are described. Most patients had significant anxiety and depressive disturbance with 42% having a personality disorder. Variation in service policies influenced recruitment, with earlier assessment centres seeing people with more frequent episodes of self-harm and greater parasuicide risk than later ones. Parasuicide risk was also significantly greater in those with their first parasuicide episode at an earlier age and in those with a more recent latest episode.

Adult↗

PubMed2002

A comparison of confidence interval methods for the intraclass correlation coefficient in cluster randomized trials.

This study compared different methods for assigning confidence intervals to the analysis of variance estimator of the intraclass correlation coefficient (rho). The context of the comparison was the use of rho to estimate the variance inflation factor when planning cluster randomized trials. The methods were compared using Monte Carlo simulations of unbalanced clustered data and data from a cluster randomized trial of an intervention to improve the management of asthma in a general practice setting. The coverage and precision of the intervals were compared for data with different numbers of clusters, mean numbers of subjects per cluster and underlying values of rho. The performance of the methods was also compared for data with Normal and non-Normally distributed cluster specific effects. Results of the simulations showed that methods based upon the variance ratio statistic provided greater coverage levels than those based upon large sample approximations to the standard error of rho. Searle's method provided close to nominal coverage for data with Normally distributed random effects. Adjusted versions of Searle's method to allow for lack of balance in the data generally did not improve upon it either in terms of coverage or precision. Analyses of the trial data, however, showed that limits provided by Thomas and Hultquist's method may differ from those of the other variance ratio statistic methods when the arithmetic mean differs markedly from the harmonic mean cluster size. The simulation results demonstrated that marked non-Normality in the cluster level random effects compromised the performance of all methods. Confidence intervals for the methods were generally wide relative to the underlying size of rho suggesting that there may be great uncertainty associated with sample size calculations for cluster trials where large clusters are randomized. Data from cluster based studies with sample sizes much larger than those typical of cluster randomized trials are required to estimate rho with a reasonable degree of precision.

Adolescent↗

PubMed2002

Patients' attitudes to medicines and expectations for prescriptions.

BACKGROUND: Recent research has shown that patients' expectations for prescriptions influence doctors' prescribing decisions, but little is known of the antecedents of these expectations. OBJECTIVES: To test earlier qualitative research about patients' views of medicines; to describe the demographic characteristics of those holding orthodox and unorthodox views of medicines; to investigate the relationship between patients' ideal and predicted expectations for prescriptions; and to determine the relative effects of attitudinal, demographic, organizational and illness variables on these expectations. DESIGN: Questionnaire survey of patients consulting general practitioners. SETTING AND PARTICIPANTS: A total of 544 patients and 15 doctors in four general practices. MAIN VARIABLES STUDIED: Patients' attitudes to medicines; patients' demographic characteristics; organizational variables; aspects of patients' presenting problems. OUTCOME MEASURES: Patients' ideal and predicted expectations for prescriptions. RESULTS: Orthodox and unorthodox attitudes to medicines can be measured quantitatively, and ethnicity was the only demographic variable associated with both. Ideal and predicted expectations for prescriptions were closely related to each other but differed in their antecedents. Both types of expectations were associated with attitudinal, demographic, organizational and illness variables. Ideal expectations were influenced by orthodox and unorthodox attitudes to medicines, while predicted expectations were only influenced by orthodox attitudes. CONCLUSIONS: Future studies of patients' expectations for health services should distinguish between ideal and predicted expectations, and should consider the range of possible influences on these expectations. In particular, the effect of the organization and context of health services should be investigated.

Adult↗