Daphne Kounali | University of Bristol (original) (raw)

Papers by Daphne Kounali

This is a protocol detailing the planned analyses for a number of studies within a single project... more This is a protocol detailing the planned analyses for a number of studies within a single project. The studies are related by drawing on the same sample or subsets of the overall sample, and sharing one of two broad aims (detailed below). The purpose of the overall project is to investigate a patient-centred metric of change during routinely delivered psychological therapy for depression or anxiety disorders among adults in Improving Access to Psychological Therapies (IAPT) services. To do this, the project aims to calculate minimum clinically important differences (MCIDs) for symptom change before and once ending therapy; that is, the smallest amount of change pre-post treatment needed on a measure of symptoms for it to be deemed important by a patient.

SSRN Electronic Journal, 2021

Background: An accurate risk prediction algorithm could improve psychosis outcomes by reducing du... more Background: An accurate risk prediction algorithm could improve psychosis outcomes by reducing duration of untreated psychosis. The objective was to develop and validate a risk prediction model for psychosis, for use by family doctors, using linked electronic health records. Methods: A prospective prediction study. Records from family practices were used between 1/1/2010 to 31/12/2017 of 300,000 patients who had consulted their family doctor for any nonpsychotic mental health problem. Records were selected from Clinical Practice Research Datalink Gold, a routine database of UK family doctor records linked to Hospital Episode Statistics, a routine database of UK secondary care records. Each patient had 5 to 8 years of follow up data. Study predictors were consultations, diagnoses and/or prescribed medications, during the study period or historically, for 13 nonpsychotic mental health problems and behaviours, age, gender, number of mental health consultations, social deprivation, geo...

Epidemiology and Infection, 2019

We evaluate the utility of the National Surveys of Attitudes and Sexual Lifestyles (Natsal) under... more We evaluate the utility of the National Surveys of Attitudes and Sexual Lifestyles (Natsal) undertaken in 2000 and 2010, before and after the introduction of the National Chlamydia Screening Programme, as an evidence source for estimating the change in prevalence of Chlamydia trachomatis (CT) in England, Scotland and Wales. Both the 2000 and 2010 surveys tested urine samples for CT by Nucleic Acid Amplification Tests (NAATs). We examined the sources of uncertainty in estimates of CT prevalence change, including sample size and adjustments for test sensitivity and specificity, survey non-response and informative non-response. In 2000, the unadjusted CT prevalence was 4.22% in women aged 18–24 years; in 2010, CT prevalence was 3.92%, a non-significant absolute difference of 0.30 percentage points (95% credible interval −2.8 to 2.0). In addition to uncertainty due to small sample size, estimates were sensitive to specificity, survey non-response or informative non-response, such that p...

Research Synthesis Methods, 2015

Objective: Trials often may report several similar outcomes measured on different test instrument... more Objective: Trials often may report several similar outcomes measured on different test instruments. We explored a method for synthesising treatment effect information both within and between trials and for reporting treatment effects on a common scale as an alternative to standardisation Study design: We applied a procedure that simultaneously estimates a pooled treatment effect and the "mapping" ratios between the treatment effects on test instruments in a connected network. Standardised and non-standardised treatment effects were compared. The methods were illustrated in a dataset of 22 trials of selective serotonin reuptake inhibitors against placebo for social anxiety disorder, each reporting treatment effects on between one and six of a total nine test instruments. Results: Ratios of treatment effects on different test instruments varied from trial to trial, with a coefficient of variation of 18% (95% credible interval 11-29%). Standardised effect models fitted the data less well, and standardised treatment effects were estimated with less relative precision than non-standardised effects and with greater relative heterogeneity. Conclusion: Simultaneous synthesis of treatment effects and mapping to a common scale make fewer assumptions than standardising by dividing effects by the sample standard deviation, allow results to be reported on a common scale, and deliver estimates with superior relative precision.

Value in Health, 2014

A new method is presented for both synthesizing treatment effects on multiple outcomes subject to... more A new method is presented for both synthesizing treatment effects on multiple outcomes subject to measurement error and estimating coherent mapping coefficients between all outcomes. It can be applied to sets of trials reporting different combinations of patient-or clinician-reported outcomes, including both diseasespecific measures and generic health-related quality-of-life measures. It is underpinned by a structural equation model that includes measurement error and latent common treatment effect factor. Treatment effects can be expressed on any of the test instruments that have been used. Methods: This is illustrated in a synthesis of eight placebo-controlled trials of TNF-α inhibitors in ankylosing spondylitis, each reporting treatment effects on between two and five of a total six test instruments. Results: The method has advantages over other methods for synthesis of multiple outcome data, including standardization and multivariate normal synthesis. Unlike standardization, it allows synthesis of treatment effect information from test instruments sensitive to different underlying constructs. It represents a special case of previously proposed multivariate normal models for evidence synthesis, but unlike the former, it also estimates mappings. Combining synthesis and mapping as a single operation makes more efficient use of available data than do current mapping methods and generates treatment effects that are consistent with the mappings. A limitation, however, is that it can only generate mappings to and from those instruments on which some trial data exist. Conclusions: The method should be assessed in a wide range of data sets on different clinical conditions, before it can be used routinely in health technology assessment.

Full extraction table. Contains the full original extracted data from each article included in th... more Full extraction table. Contains the full original extracted data from each article included in the review (XLSX 35 kb)

SPIRIT 2013 Checklist: recommended items to address in a clinical trial protocol and related docu... more SPIRIT 2013 Checklist: recommended items to address in a clinical trial protocol and related documents. (DOC 122 kb)

Abstract: Models are developed to adjust for measurement errors in normally distributed predictor... more Abstract: Models are developed to adjust for measurement errors in normally distributed predictor and response variables and categorical predictors with misclassification errors. The models allow for a hierarchical data structure and for correlations among the errors and misclassifications. Markov Chain Monte Carlo (MCMC) estimation is used and implemented in a set of MATLAB macros. Key words: multilevel model; measurement errors; misclassification errors; MCMC estimation

Multilevel multivariate modelling of childhood growth, numbers of growth measurements and adult c... more Multilevel multivariate modelling of childhood growth, numbers of growth measurements and adult characteristics

The debate has been ‘alive’ since the publication of Coleman’s et al’s (1966) celebrated report b... more The debate has been ‘alive’ since the publication of Coleman’s et al’s (1966) celebrated report because it is central to two related concerns: the nature of school effectiveness and appropriate policies to raise school effectiveness. With respect to the former Thrupp and Hirsch (2006) have argued that we can identify two ideal typical positions, the first claims that school effectiveness is a function of school management and teacher performance, while the latter claims that social factors (e.g., social class) determine pupil outcomes in schools. In this respect, pupil composition can be seen as one social factor that may be significant in determining pupil outcomes. However, they note that we can consider these two positions as at the ends of a spectrum and that much of the debate centres on the relative contributions of schools and teachers and social factors.

The British Journal of Psychiatry

Background Psychotic experiences are reported by 5–10% of young people, although only a minority ... more Background Psychotic experiences are reported by 5–10% of young people, although only a minority persist and develop into psychotic disorders. It is unclear what characteristics differentiate those with transient psychotic experiences from those with persistent psychotic experiences that are more likely to be of clinical relevance. Aims To investigate how longitudinal profiles of psychotic experiences, created from assessments at three different time points, are influenced by early life and co-occurring factors. Method Using data from 8045 individuals from a birth cohort study, longitudinal profiles of psychotic experiences based on semi-structured interviews conducted at 12, 18 and 24 years were defined. Environmental, cognitive, psychopathological and genetic determinants of these profiles were investigated, along with concurrent changes in psychopathology and cognition. Results Following multiple imputations, the distribution of longitudinal profiles of psychotic experiences was ...

SSRN Electronic Journal

ImportanceCOVID-19 public health mitigation measures are likely to have detrimental effects on em... more ImportanceCOVID-19 public health mitigation measures are likely to have detrimental effects on emotional and behavioural problems in children. However, longitudinal studies with pre-pandemic data are scarce.ObjectiveTo explore trajectories of children’s emotional and behavioural difficulties during the COVID-19 pandemic.Design and settingData were from children from the third generation of a birth cohort study; the Avon Longitudinal Study of Parents and Children - Generation 2 (ALSPAC-G2) in the southwest of England.ParticipantsThe study population comprised of 708 children (median age at COVID-19 data collection was 4.4 years, SD=2.9, IQR= [2.2 to 6.9]), whose parents provided previous pre-pandemic surveys and a survey between 26 May and 5 July 2020 that focused on information about the COVID-19 pandemic as restrictions from the first lockdown in the UK were eased.ExposuresWe employed multi-level mixed effects modelling with random intercepts and slopes to examine whether children’s trajectories of emotional and behavioural difficulties (a combined total difficulties score) during the pandemic differ from expected pre-pandemic trajectories.Main outcomesChildren had up to seven measurements of emotional and behavioural difficulties from infancy to late childhood, using developmentally appropriate scales such as the Emotionality Activity Sociability Temperament Survey in infancy and Strengths and Difficulties Questionnaire in childhood.ResultsThe observed normative pattern of children’s emotional and behavioural difficulties pre-pandemic, was characterised by an increase in scores during infancy peaking around the age of 2, and then declining throughout the rest of childhood. Pre-pandemic, the decline in difficulties scores after age 2 was 0.6 points per month; but was approximately one third of that in post-pandemic trajectories (there was a difference in mean rate of decline after age 2 of 0.2 points per month in pre vs during pandemic trajectories [95 % CI: 0.10 to 0.30, p <0.001]). This lower decline in scores over the years translated to older children having pandemic difficulty scores higher than would be expected from pre-pandemic trajectories (for example, an estimated 10.0 point (equivalent of 0.8 standard deviations) higher score (95% CI: 5.0 to 15.0) by age 8.5 years). Results remained similar although somewhat attenuated after adjusting for maternal anxiety and age.Conclusion and relevanceThe COVID-19 pandemic may be associated with greater persistence of emotional and behavioural difficulties after the age 2. Emotional difficulties in childhood predict later mental health problems. Further evidence and monitoring of emotional and behavioural difficulties are required to fully understand the potential role of the pandemic on young children.Key FindingsQuestionHow has the COVID-19 pandemic influenced emotional difficulties in young children?FindingsUsing repeated longitudinal data from before and during the pandemic we provide evidence that emotional difficulty scores of primary school aged children are higher by an estimated 10.0 points (0.8 standard deviations) (95% CI: 5.0 to 15.0) by age 8.5 years than would be expected based on pre pandemic data.MeaningThe level of difference in emotional difficulties found in the current study has been linked to increased likelihood of mental health problems in adolescence and adulthood. Therefore, this increase in difficulties needs careful monitoring and support.

Psychological Medicine

Background The Patient Health Questionnaire (PHQ-9), the Beck Depression Inventory (BDI-II) and t... more Background The Patient Health Questionnaire (PHQ-9), the Beck Depression Inventory (BDI-II) and the Generalised Anxiety Disorder Assessment (GAD-7) are widely used in the evaluation of interventions for depression and anxiety. The smallest reduction in depressive symptoms that matter to patients is known as the Minimum Clinically Important Difference (MCID). Little empirical study of the MCID for these scales exists. Methods A prospective cohort of 400 patients in UK primary care were interviewed on four occasions, 2 weeks apart. At each time point, participants completed all three questionnaires and a ‘global rating of change’ scale (GRS). MCID estimation relied on estimated changes in symptoms according to reported improvement on the GRS scale, stratified by baseline severity on the Clinical Interview Schedule (CIS-R). Results For moderate baseline severity, those who reported improvement on the GRS had a reduction of 21% (95% confidence interval (CI) −26.7 to −14.9) on the PHQ-9;...

Schizophrenia Bulletin

Background At present clinical high-risk states for psychosis are determined by specialist mental... more Background At present clinical high-risk states for psychosis are determined by specialist mental health services using clinical tools such as the CAARMS, which largely rely on the detection of attenuated psychotic symptoms. However, the positive predictive value (PPV) of the CAARMS for transition to psychosis is only 25% in help seeking populations and as low as 5% in general population, non-help seeking samples. There is therefore a clear need to improve the prediction of psychotic disorder using other (non-symptom related) markers of risk. Our aim was to derive a risk prediction tool to determine risk of psychotic disorder using a large, population-based birth-cohort. Methods We used data from the ALSPAC birth cohort, with data on a comprehensive range of predictors ascertained from early childhood through early adulthood, and on psychotic disorder up to age 24 (imputed up to N≈7000 with any data on psychotic experiences). We use a two-stage risk prediction model, where different...

Schizophrenia Bulletin

Background Given the global burden of disease of psychotic disorders and the promise of benefit f... more Background Given the global burden of disease of psychotic disorders and the promise of benefit from early intervention, there is an imperative to understand the developmental trajectories from onset of psychotic experiences to clinical disorder and to improve identification of individuals at greatest risk. The aims of this study therefore were: 1) to describe, for the first time, the change in incidence of psychotic experiences in the general population from childhood through early adulthood; 2) to describe the prevalence and burden of unmet clinical need of at-risk mental states and psychotic disorder among young adults in the general population; 3) to examine the predictive ability of both self-reported and interviewer-rated measures of psychotic experiences during childhood and adolescence in identifying psychotic disorder by early adulthood; and 4) to describe longitudinal profiles of psychotic experiences from childhood through early adulthood and investigate a comprehensive r...

Psychological Medicine

Background Self-administered questionnaires are widely used in primary care and other clinical se... more Background Self-administered questionnaires are widely used in primary care and other clinical settings to assess the severity of depressive symptoms and monitor treatment outcomes. Qualitative studies have found that changes in questionnaire scores might not fully capture patients' experience of changes in their mood but there are no quantitative studies of this issue. We examined the extent to which changes in scores from depression questionnaires disagreed with primary care patients' perceptions of changes in their mood and investigated factors influencing this relationship. Methods Prospective cohort study assessing patients on four occasions, 2 weeks apart. Patients (N = 554) were recruited from primary care surgeries in three UK sites (Bristol, Liverpool and York) and had reported depressive symptoms or low mood in the past year [68% female, mean age 48.3 (s.d. 12.6)]. Main outcome measures were changes in scores on patient health questionnaire (PHQ-9) and beck depress...

American Journal of Psychiatry

Programme Grants for Applied Research

Background Despite a growing number of prescriptions for antidepressants (over 70 million in 2018... more Background Despite a growing number of prescriptions for antidepressants (over 70 million in 2018), there is uncertainty about when people with depression might benefit from antidepressant medication and concern that antidepressants are prescribed unnecessarily. Objectives The main objective of the PANDA (What are the indications for Prescribing ANtiDepressAnts that will lead to a clinical benefit?) research programme was to provide more guidance about when antidepressants are likely to benefit people with depression. We aimed to estimate the minimal clinically important difference for commonly used self-administered scales for depression and anxiety, and to understand more about how patients respond to such assessments. We carried out an observational study of patients with depressive symptoms and a placebo-controlled randomised controlled trial of sertraline versus placebo to estimate the treatment effect in UK primary care. The hypothesis was that the severity and duration of sym...

SSRN Electronic Journal, 2021

Epidemiology and Infection, 2019

Research Synthesis Methods, 2015

Value in Health, 2014

The British Journal of Psychiatry

SSRN Electronic Journal

Psychological Medicine

Schizophrenia Bulletin

Psychological Medicine

American Journal of Psychiatry

Programme Grants for Applied Research