Search PubMed⌕ Search

Biomedical subjects

D W Chadwick

Publications and source records attributed to D W Chadwick.

At least 55 records · Page 3Linked to original sources
PubMed1998

Practice styles of US compared to UK neurologists.

OBJECTIVE: This study assessed variation between neurologists in the United States and United Kingdom in their diagnostic and treatment decisions for commonly encountered neurologic presentations, and identified explanatory factors for any observed variation. METHODS: All 210 consultant neurologists in the United Kingdom and a nationally representative sample of 595 US neurologists received mailed surveys containing three detailed clinical scenarios depicting patients with (1) a single unprovoked seizure occurring 3 days previously, (2) early Parkinson's disease, and (3) dementia. The main study outcome measures were self-reported decisions regarding diagnostic test ordering and treatment, which were assessed after each scenario. Neurologists' practice characteristics, certainty about the diagnosis, and attitudes toward uncertainty were also measured. Survey response rates were 92% of US and 63% of UK neurologists. RESULTS: A higher proportion of US than UK neurologists indicated they would order additional diagnostic tests for all three scenarios (all p < 0.05); 77% of UK compared with 26% of US neurologists would manage a single unprovoked seizure without antiepileptic medication (p < 0.0001), but treatment of early Parkinson's disease was not different. Nearly all US and UK neurologists would obtain a neuroimaging study in the evaluation of dementia. International differences persisted after adjustment for differences in demographic and practice characteristics and for attitudes toward test use and clinical uncertainty. CONCLUSIONS: We identified large international variation in clinical decisions across three common neurologic conditions. Cross-country collaboration should explore these differences to develop consensus on standards of care.

Attitude of Health Personnel↗
PubMed1998

A double-blind trial of gabapentin monotherapy for newly diagnosed partial seizures. International Gabapentin Monotherapy Study Group 945-77.

BACKGROUND: Gabapentin is widely approved as add-on therapy for epilepsy treatment for partial seizures with and without secondary generalization. To investigate the efficacy of gabapentin administered as monotherapy in patients with newly diagnosed partial epilepsy, a randomized double-blind trial was performed. METHODS: Eligible patients were randomized to receive one of three masked doses of gabapentin (300, 900, or 1,800 mg/day) or open-label carbamazepine (600 mg/day) and kept daily seizure diaries throughout the study. After titration, patients entered a 24-week evaluation phase. Patients were required to exit the study if they experienced an exit event, defined as a total of three simple or complex partial seizures, one generalized tonic-clonic (GTC) seizure, or status epilepticus. Patients could be withdrawn for lack of efficacy, adverse events, or noncompliance. Kaplan-Meier statistics were used to estimate the probability that patients would continue in the study without having an exit event. RESULTS: Time to exit event was longer for patients on 900 mg/day (n = 72) or 1,800 mg/day (n = 74) of gabapentin than for patients receiving 300 mg/day (n = 72; p = 0.0395 and 0.0175, respectively). The most clinically relevant measure of retention on treatment (exit event plus adverse event withdrawal rate) was similar for carbamazepine (n = 74) and 1,800 mg/day gabapentin (54% versus 57%) but was lower (better) for 900 mg/day gabapentin (44%). No unexpected new adverse events emerged with gabapentin monotherapy. CONCLUSIONS: Gabapentin at 900 or 1,800 mg/day is effective and safe as monotherapy for patients with newly diagnosed partial epilepsy.

Acetates↗
PubMed1997

Factors influencing compliance with antiepileptic drug regimes.

Failure to comply with drug regimes is prevalent amongst patients with epilepsy and the consequence of this is often an increased risk of further seizures. This paper describes the level of, and influences upon, non-compliance with antiepileptic drug (AED) treatment. A postal questionnaire was sent to an unselected, community-based population of patients with epilepsy. This instrument included questions about patients' AED treatment, any related side-effects, and AED-taking behaviour. Univariate analysis showed that factors associated with compliance were patient age, how important patients felt it was to take drugs as prescribed, whether patients reported feelings of stigma, whether on mono- or polytherapy, whether they were experiencing any side-effects because of AEDs, whether patients had a regular arrangement to see their GP about epilepsy and how easy they found their GP to talk to. Multivariate analysis showed that the strongest predictors of non-compliance were feeling it was not very or not at all important to take AEDs as prescribed, being a teenager, being aged under 60 and being on monotherapy. Further implementation of educational programmes for people with epilepsy would help to improve levels of compliance thereby reducing the risk of unnecessary seizures.

Adaptation, Psychological↗
PubMed1997

The new antiepileptic drugs: a systematic review of their efficacy and tolerability.

PURPOSE: Gabapentin (GBP), lamotrigine (LTG), tiagabine (TGB), topiramate (TPM), vigabatrin (VGB), and zonisamide (ZNS) are all in use as "add-on" treatment for patients with refractory epilepsy. There have been no comparative randomized controlled trials allowing an evidence-based choice between these drugs. We report a series of meta-analyses of randomized placebo-controlled add-on trials in which these drugs have been tested in patients with partial epilepsy. This work provides an estimate of each drug's efficacy and tolerability compared with placebo. These estimates are compared across drugs to give broad estimates of comparative efficacy and tolerability. METHODS: Trial reports were found by searching Medline, by searching through journals by hand, and by contacting the pharmaceutical industry. The outcomes chosen were the proportion of patients who (a) have a > or = 50% reduction in seizure frequency (50% responders); (b) withdrew from the study (any reason); or (c) reported the following side effects: ataxia, dizziness, fatigue, nausea, or somnolence. Overall odds ratio (OR) with 95% confidence intervals (CIs; 50% responders) or 99% CIs; side effects) were calculated. RESULTS: Twenty-nine trials were included, representing 4,091 randomized patients. The ORs for 50% response (95% CI) were GBP, 2.29 (1.53-3.43); LTG, 2.32 (1.47-3.68); TGB, 3.03 (2.01-4.58); TPM, 4.07 (2.87-5.78); VGB, 3.67 (2.44-5.51); and ZNS, 2.7 (1.36-4.47). ORs for discontinuation were GBP, 1.36 (0.75-2.49); LTG, 1.19 (0.79-1.79); TGB, 1.81 (1.21-2.70); TPM, 2.56 (1.64-4.00); VGB, 2.58 (126-5.27); and ZNS, 4.23 (1.71-10.49). CONCLUSIONS: We have clear evidence that each of these drugs is better than placebo at preventing seizures. When results are compared across drugs, the confidence intervals overlap, and we have no conclusive evidence of differences in efficacy or tolerability. Despite this, the agent that appears most effective may be twice as effective as the agent that appears least effective, and the agent that appears most likely to cause discontinuation may be 4 times more likely to do so than the treatment that appears least likely to do so. Comparative randomized studies are needed further to evaluate these drugs.

Acetates↗
PubMed1997

Patients' experiences of injury as a result of epilepsy.

PURPOSE: The increased risk of mortality among people with epilepsy is well documented; people with epilepsy are more likely than the general population to die as a result of an accident. Data about incidence of nonfatal accidents and associated factors are not so readily available, even though such accidents are more common than fatal injuries. We report the proportion of people who sustain various injuries during a seizure and the key variables predicting injury. METHODS: Questionnaires were mailed to an unselected, community-based population of patients with epilepsy. The questionnaire included clinical and demographic details, previously validated scales of psychosocial well-being, and questions about seizure-related injuries. RESULTS: Of patients who had had at least one seizure during the previous year, 24% sustained at least one head injury, 16% sustained a burn or scald, 10% a dental injury, and 6% some other fracture. Seizure type, seizure severity, and seizure frequency were key predictors of having sustained at least one of these four seizure-related injuries. Key predictors of burn/scald were seizure severity, seizure frequency and sex; those of head injury were seizure severity and type; that of dental injury was seizure severity; and those of some other fracture were seizure severity, duration of epilepsy, and three or more drug-related adverse effects. CONCLUSIONS: These data help identify significant risk factors associated with seizure-related injuries and so facilitate sensible patient counseling about how the risks of such injuries can be minimized.

Accidents↗
PubMed1997

An overview of the efficacy and tolerability of new antiepileptic drugs.

To evaluate the efficacy and tolerability of recently developed antiepileptic drugs (AEDs), a systematic review of placebo-controlled, randomized controlled trials (RCTs) of the AEDs as add-on therapy in refractory partial epilepsy was conducted. Two or more RCTs meeting our inclusion criteria were found for gabapentin (GBP), lamotrigine (LTG), tiagabine (TGB), topiramate (TPM), vigabatrin (VGB), and zonisamide (ZNS). The outcome selected for estimation of efficacy was the proportion of patients experiencing a > or = 50% reduction in seizure frequency from baseline. Tolerability was estimated on the basis of rates of patient withdrawal from study for any reason. Efficacy and tolerability odds ratios (ORs) and 95% confidence intervals (95% CIs) for each measure were generated for each trial included in the analysis, and overall efficacy and tolerability ORs were calculated for each AED across all trials and drug dosages evaluated. Because 95% CIs for both efficacy and tolerability overlapped for the six drugs, conclusive evidence of between-drug differences in effectiveness or safety were not obtained from the analysis. However, the data suggest that the drug with the highest OR for efficacy (TPM) may be approximately twice as effective as the AED with the lowest OR for efficacy (GBP), and that the treatment that appears to most frequently cause withdrawal (ZNS) may be about four times more likely to do so that the AED with the lowest withdrawal rate (LTG). RCTs comparing newer AEDs with the older standard drugs and with each other are needed to further evaluate their relative utility.

Anticonvulsants↗
PubMed1997

Quality of life after epilepsy surgery.

OBJECTIVE: To assess the relation between seizure status and quality of life after surgery for drug resistant epilepsy, using a previously validated quality of life model developed for use in epilepsy. METHODS: A retrospective postal survey was made on 94 patients who underwent surgery for epilepsy between 1986 and 1994, and 36 patients who after investigation during the same period were found to be unsuitable for surgery. A health related quality of life model was used containing validated measures of anxiety, depression, self esteem, mastery, impact of epilepsy, affect balance, stigma, overall health status, and overall quality of life, to examine the relation between postoperative seizure status and quality of life. RESULTS: Overall 47.9% of patients were seizure free after surgery. On all measures seizure free patients scored significantly better than either patients deemed unsuitable for surgery or those having more than 10 seizures per year after surgery. Patients having less than 10 seizures per year obtained intermediate scores. There was no difference between the groups unsuitable for surgery or having more than 10 seizures per year postoperatively. Employment rates were significantly different between groups, 80% of seizure free and 53% of patients having less than 10 seizures per year in gainful employment postoperatively, compared with 28% and 27% of patients having greater than 10 seizures per year or those who were unsuitable for surgery. CONCLUSIONS: Within broad categories, postoperative quality of life is clearly related to seizure outcome, but the study emphasises the importance of long term follow up in defining the tangible psychosocial effects of freedom from seizures.

Amygdala↗
PubMed1997

Implications of socio-cultural contexts for the ethics of clinical trials.

BACKGROUND: Health technology assesment (HTA) requires scientifically rigorous experimentation involving patients as subjects. HTA itself is required so that treatment given to patients will be both effective and efficient; this requirement is itself ethical in nature. At the same time it is essential that the methods used in HTA are ethically sound. Most healthcare researchers agree that the most effective and soundest method for assessing treatments is the randomised controlled trial (RCT). However, some researchers believe that the RCT is unethical, either in essence, or for use in some forms of medical research and HTA. Furthermore, many patients seem unable to understand the principles and purposes of the RCT, a factor which is highly detrimental for the validity of informed consent. Informed consent is the key to the ethics of medical research, both in most theories and in all codes of research conduct. Many RCTs therefore risk being unethical in practice, even if ethical in principle. AIM OF REPORT: To survey the main objections to the RCT and its alternatives. To assess the philosophical and methodological basis of these objections, and of the methods recommended for addressing them. To identify areas where objections are founded in social or cultural factors normally overlooked in ethical argument about the RCT methodology. To identify alternative arguments or methods which might resolve ethical conflicts in this area. HOW THE RESEARCH WAS CONDUCTED: The methods used were adapted from systematic reviews in medicine. Systematic searches of Medline, Psychlit and Sociofile CD-ROM databases; hand-searches of the major journals in general medicine and surgery, medical ethics and philosophy; and searches of books were carried out. The literature survey was restricted to articles published or abstracted in English. A database of the most relevant and useful materials was compiled, and is accessible on the Internet (http://www.liv.ac.uk/sdthomps/page1.html). RESEARCH FINDINGS: UNDERSTANDING RCTS AND THEIR ALTERNATIVES: There is some evidence of difficulty in understanding the aims and methods of RCTs, and some disquiet about elements of the RCT methodologies. These objections are well known and much discussed, and concern the use of placebo, the continuation of trials after significant differentials in benefit or harm are apparent, and randomisation. CULTURAL OR RELIGIOUS OBJECTIONS: There was an absence of evidence of cultural or religious objections to randomisation, placebo or other kinds of controlled prospective trials. This most likely reflects an absence of research rather than absence of objections. (ABSTRACT TRUNCATED)

Cultural Diversity↗
PubMed1996

New antiepileptic drugs: a systematic review of their efficacy and tolerability.

OBJECTIVES: To evaluate the efficacy and tolerability of the newly developed antiepileptic drugs gabapentin, lamotrigine, tiagabine, topiramate, vigabatrin, and zonisamide in patients with refractory partial epilepsy. DESIGN: Systematic review of published and unpublished randomised controlled trials of add-on treatment with new antiepileptic drugs. SUBJECTS: 20 published and eight unpublished trials representing 3883 patients with refractory partial epilepsy. MAIN OUTCOME MEASURES: Proportion of patients who (a) showed 50% or greater reduction in frequency of seizures (50% responders) and (b) withdrew from each study for any reason. RESULTS: Odds ratios (95% confidence intervals) relative to placebo for 50% responders were 2.29 (1.53 to 3.43) for gabapentin, 2.32 (1.47 to 3.68) for lamotrigine, 3.03 (2.01 to 4.58) for tiagabine, 4.22 (2.80 to 6.35) for topiramate, 3.68 (2.45 to 5.51) for vigabatrin, and 2.47 (1.36 to 4.47) for zonisamide. Odds ratios for withdrawal were 1.36 (0.75 to 2.49) for gabapentin, 1.19 (0.79 to 1.79) for lamotrigine, 1.81 (1.21 to 2.70) for tiagabine, 2.42 (1.43 to 4.11) for topiramate, 2.58 (1.26 to 5.27) for vigabatrin, and 5.70 (1.76 to 18.49) for zonisamide. Comparing results for each drug showed that all of the 95% confidence intervals overlapped, indicating that they were not significantly different in terms of efficacy and tolerability. CONCLUSIONS: All six drugs were significantly better than placebo at reducing frequency of seizures. These results do not allow an evidence based choice between these drugs as we have no conclusive indication of differences in efficacy or tolerability.

Acetates↗
PubMed1996

The associations of psychopathology in epilepsy: a community study.

There is a plethora of studies documenting the association between psychosocial disadvantage and epilepsy but a paucity of studies explaining the precise nature of that relationship. Previous studies have been hampered by methodological problems including small sample size and selection bias. This study examined the aetiology of psychopathology in epilepsy in a cross-sectional community study. A significant proportion of patients were anxious and depressed and many reported side effects of their medication. Stepwise multiple regression techniques were employed to examine the relationship between clinical, demographic and psychosocial variables. Results indicated that psychosocial variables were the best predictors of each other but when these were taken into account, patient perceived seizure severity was an important predictor variable in understanding the relationship between epilepsy and psychosocial functioning.

Adult↗
PubMed1996

The clinical course of epilepsy and its psychosocial correlates: findings from a U.K. Community study.

As part of a large community-based study, we retrospectively examined the clinical course of epilepsy in an unselected population of people who had a recent history of seizures or were receiving antiepileptic drugs (AEDs). Clinical information was collected from medial records, and information about psychosocial functioning was obtained by means of postal questionnaires sent to identified subjects. The response rate to the postal questionnaire was 71%. There were some deficiencies in the recording of clinical data, which is not unusual since data were taken from records held by primary physicians rather than from hospital clinics. Nevertheless, findings regarding the clinical course of epilepsy corresponded to those of earlier studies. Fifty-seven percent of the sample had had at least a 2-year seizure-free period and 46% of subjects were currently in a remission of at least 2-year duration. There was a clear relationship between current seizure frequency and levels of anxiety and depression, perceived impact of epilepsy, perceived stigma, and marital and employment status. The relationship of seizure frequency and other clinical variables to psychosocial function was explored by multivariate analysis techniques. The amount of variation in scores on the various measures of function accounted for by the clinical variables was small. The most important predictor was current seizure activity, which was the first variable to enter the regression analyses for six of the eight measures of psychosocial function considered. Age at epilepsy onset also emerged as a significant predictor for depression, stigma, and marital status. In individuals with epilepsy in remission, there was little evidence that psychosocial functioning was associated with length of remission, a finding which may in part reflect the nature of this study population. The results indicate that there are several more important predictors of psychopathology and social dysfunction in epilepsy and suggest several implications for treatment interventions.

Adult↗
PubMed1996

Patients' experiences of and satisfaction with care for their epilepsy.

PURPOSE: To determine condition-specific satisfaction with care, we studied patients' experience of general practitioner (primary physician) and hospital clinic care for their epilepsy and their views about the provision of information concerning the management of their condition. METHODS: A postal questionnaire was sent to an unselected, community-based population of patients with epilepsy. In addition to clinical and demographic details and previously validated scales of psychosocial well-being, the instrument contained a series of questions about patients' experiences and views of the care they received for epilepsy from both general practice and the hospital services. RESULTS: Doctors' interpersonal skills were the most influential factors affecting both patient satisfaction overall and the likelihood that doctors might discuss with patients certain clinical and social issues surrounding the management of the patient's condition. A sizable proportion of patients reported that they received insufficient information about epilepsy, both from hospital doctors and general practitioners. CONCLUSIONS: Patients with epilepsy place great importance on having a doctor who is approachable, communicative, and knowledgeable and on receiving adequate information about their condition. Clinicians may need to be made more aware of the importance of accessibility and sensitivity to the nonclinical needs of their patients. Such easily implemented changes in the delivery of care would improve services in the United Kingdom for people with epilepsy.

Adolescent↗
PubMed1996

How easy are randomized controlled trials in epilepsy to find on Medline? The sensitivity and precision of two Medline searches.

Recognition of the need for more scientifically acceptable review strategies is increasing. Systematic reviews have rarely been performed on randomized controlled trials (RCTs) in the field of epilepsy. We have 355 published RCTs on a database, which will be used as a data source from systematic reviews. We wished to test the sensitivity and precision of two Medline search strategies, and to identify reasons why RCTs were missed. Both a basic and a comprehensive search strategy were used to search Medline from 1966 to 1993. Three journals (Epilepsia, Epilepsy Research, Acta Neurological Scandinavica) were searched by hand. The sensitivity and precision of these Medline search strategies in these three journals was calculated. We investigated articles missed by our comprehensive search to ascertain why they had been missed. Of the 308 RCTs on the database published between 1966 and 1993, 275 were found by our comprehensive Medline search, whereas 103 were found by our basic search. The overall precision of our comprehensive and basic searches was 35 and 72%, respectively. The overall sensitivity of our comprehensive and basic searches was 86 and 66%, respectively. Our comprehensive search failed to find 16 RCTs published in the three journals searched by hand. Articles were missed because they were inadequately indexed on Medline and/or did not contain adequate methodological information in their titles or abstracts. To find all relevant trials, a search strategy must be as sensitive as possible, but this sensitivity inevitably involves loss of precision. The National Library of Medicine is addressing indexing problems with Medline, but the quality of reports also must be improved to enhance retrieval.

Abstracting and Indexing↗
PubMed1996

Clinical administration of new antiepileptic drugs: an overview of safety and efficacy.

Gabapentin, lamotrigine, tiagabine, topiramate, vigabatrin, and zonisamide are all administered as add-on therapy for treatment of patients with refractory epilepsy. To date, no comparative randomized trials have been performed that could potentially allow an evidence-based choice to be made between these antiepileptic drugs (AEDs). We report a series of meta-analyses of placebo-controlled, randomized add-on trials in patients with partial epilepsy. Results of these meta-analyses are compared, thus giving broad estimates of the comparative efficacy and tolerability of these AEDs. The efficacy outcome is the odds ratio for the number of patients with a > or = 50% reduction in seizure frequency. Reported side effects are also used as tolerability outcomes, and study withdrawal is used as a global outcome measure. Results are summarized as odds ratios with 95% confidence intervals (CIs). When each outcome is compared among drugs, the 95% CIs overlap. Therefore, no conclusive evidence of a difference in efficacy or tolerability between these AEDs was derived, even though the apparently most effective agent (topiramate) may be twice as effective as the apparently least effective agent (lamotrigine). Comparative randomized studies are needed to further evaluate these drugs.

Acetates↗
PubMed1995

Advances in methods for assessing the impact of epilepsy and antiepileptic drug therapy on patients' health-related quality of life.

We studied 31 previously validated and newly developed generic and epilepsy-specific scales to evaluate their usefulness for assessing the impact of epilepsy and anti-epileptic drug (AED) therapy on health-related quality of life (HRQOL). Included were the MOS SF-36 Health Survey, additional measures of mental health, cognition, epilepsy-specific perception of control, behavioural problems, distress, worries and experiences, the Liverpool Epilepsy Impact and Seizure Severity scales, and a patient-completed symptom checklist. Questionnaires were completed twice by 136 patients on AED therapy in a multicentre study in the UK. Validity was assessed in relation to disease severity, defined as time since last seizure, and to patient-reported symptoms. Statistical analyses to estimate the contribution of HRQOL information of each scale relative to that of others were conducted. The 171-item questionnaire could be completed by out-patients with epilepsy with good data quality. With few exceptions, generic and epilepsy-specific measures satisfied psychometric tests of hypothesized item groupings and scale score reliability (internal consistency and test-retest reliability) and differentiated well between groups of patients differing in time since last seizure and in symptom impact, regardless of time since last seizure. However, scales differed widely in their validity in discriminating between groups of patients known to differ clinically. The SF-36 Role Physical scale best discriminated among groups differing in disease severity. The epilepsy-specific Mastery, Impact, Experience, Worry, Distress, and Agitation scales were among the 10 best measures in discriminating among groups differing in disease severity. Generic measures, especially measures of social and role functioning and mental health, were best at differentiating groups of patients differing in symptom impact. Recommendations are offered for concepts and specific scales most likely to be useful in future studies of the HRQOL burden of epilepsy and the HRQOL benefits of AED therapy.

Adolescent↗
PubMed1995

Adjunctive treatment of partial seizures with tiagabine: a placebo-controlled trial.

Tiagabine is a new antiepileptic drug which acts by a novel mechanism, inhibiting the reuptake of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) into neurons and glia. A double-blind, placebo-controlled, crossover trial was undertaken, based upon a response-dependent design. Ninety-four patients with complex partial seizures with or without secondary generalised tonic-clonic seizures were recruited into an open screening phase and tiagabine was added to their existing drug therapy in doses titrated to reduce seizure frequency by > or = 25% or to the limit of tolerance. Forty-six responders were subsequently randomised to a double-blind crossover trial in which tiagabine was compared with placebo. Forty-two patients completed the trial. A significant reduction in the frequency of complex partial and secondary generalised tonic clonic seizures was seen. Twenty-six percent had a reduction of > or = 50% in the frequency of their complex partial seizures, and of the 27 patients who also had secondary generalised tonic clonic seizures, 63% experienced a reduction of > or = 50%. No interactions with baseline antiepileptic drugs were detected and no serious adverse reactions occurred. The commonest adverse events were tiredness, dizziness and headache. We conclude that tiagabine has promising antiepileptic effects. Further trials are underway.

Adolescent↗
PubMed1995

Prospective evaluation of a prognostic index for intrinsic supratentorial tumours.

A prognostic index for patients with intrinsic supratentorial tumours based on prebiopsy findings was proposed on the basis of data bases of patients presenting between 1975 and 1989. The value of this index is confirmed from data on 76 patients who presented during 1991. Patients classified by the index as having a poor prognosis had a median survival of six months, and those classified as having a good prognosis had a median survival of five years. The expected duration of survival, allowing for this initial prognosis, also depended on whether a patient received resective surgery, radiotherapy, or steroids. Histological grade provided no additional information on survival.

Epilepsy↗