Statistical analysis plan for the motor neuron disease systematic multi-arm adaptive randomised trial (MND-SMART)

BACKGROUND

MND-SMART is a platform, multi-arm, multi-stage, multi-centre, randomised controlled trial recruiting people with motor neuron disease. Initially, the treatments memantine and trazodone will each be compared against placebo, but other investigational treatments will be introduced into the trial later. The co-primary outcomes are the Amyotrophic Lateral Sclerosis Functional Rating Scale Revised (ALS-FRS-R) functional outcome, which is assessed longitudinally, and overall survival.

METHODS

Initially in MND-SMART, participants are randomised 1:1:1 via a minimisation algorithm to receive placebo or one of the two investigational treatments with up to 531 to be randomised in total. The comparisons between each research arm and placebo will be conducted in four stages, with the opportunity to cease further randomisations to poorly performing research arms at the end of stages 1 or 2. The final ALS-FRS-R analysis will be at the end of stage 3 and final survival analysis at the end of stage 4. The estimands for the co-primary outcomes are described in detail. The primary analysis of ALS-FRS-R at the end of stages 1 to 3 will involve fitting a normal linear mixed model to the data to calculate a mean difference in rate of ALS-FRS-R change between each research treatment and placebo. The pairwise type 1 error rate will be controlled, because each treatment comparison will generate its own distinct and separate interpretation. This publication is based on a formal statistical analysis plan document that was finalised and signed on 18 May 2022.

DISCUSSION

In developing the statistical analysis plan, we had to carefully consider several issues such as multiple testing, estimand specification, interim analyses, and statistical analysis of the repeated measurements of ALS-FRS-R. This analysis plan attempts to balance multiple factors, including minimisation of bias, maximising power and precision, and deriving clinically interpretable summaries of treatment effects.

TRIAL REGISTRATION

EudraCT Number, 2019-000099-41. Registered 2 October 2019, https://www.clinicaltrialsregister.eu/ctr-search/search?query=mnd-smart ClinicalTrials.gov, NCT04302870 . Registered 10 March 2020.

Motor Neuron Disease Systematic Multi-Arm Adaptive Randomised Trial (MND-SMART): a multi-arm, multi-stage, adaptive, platform, phase III randomised, double-blind, placebo-controlled trial of repurposed drugs in motor neuron disease

INTRODUCTION

Motor neuron disease (MND) is a rapidly fatal neurodegenerative disease. Despite decades of research and clinical trials there remains no cure and only one globally approved drug, riluzole, which prolongs survival by 2-3 months. Recent improved mechanistic understanding of MND heralds a new translational era with many potential targets being identified that are ripe for clinical trials. Motor Neuron Disease Systematic Multi-Arm Adaptive Randomised Trial (MND-SMART) aims to evaluate the efficacy of drugs efficiently and definitively in a multi-arm, multi-stage, adaptive trial. The first two drugs selected for evaluation in MND-SMART are trazodone and memantine.

METHODS AND ANALYSIS

Initially, up to 531 participants (177/arm) will be randomised 1:1:1 to oral liquid trazodone, memantine and placebo. The coprimary outcome measures are the Amyotrophic Lateral Sclerosis Functional Rating Scale Revised (ALSFRS-R) and survival. Comparisons will be conducted in four stages. The decision to continue randomising to arms after each stage will be made by the Trial Steering Committee who receive recommendations from the Independent Data Monitoring Committee. The primary analysis of ALSFRS-R will be conducted when 150 participants/arm, excluding long survivors, have completed 18 months of treatment; if positive the survival effect will be inferentially analysed when 113 deaths have been observed in the placebo group. The trial design ensures that other promising drugs can be added for evaluation in planned trial adaptations. Using this novel trial design reduces time, cost and number of participants required to definitively (phase III) evaluate drugs and reduces exposure of participants to potentially ineffective treatments.

ETHICS AND DISSEMINATION

MND-SMART was approved by the West of Scotland Research Ethics Committee on 2 October 2019. (REC reference: 19/WS/0123) Results of the study will be submitted for publication in a peer-reviewed journal and a summary provided to participants.

TRIAL REGISTRATION NUMBERS

European Clinical Trials Registry (2019-000099-41); NCT04302870.

The novel MAPT mutation K298E: mechanisms of mutant tau toxicity, brain pathology and tau expression in induced fibroblast-derived neurons

Frontotemporal lobar degeneration (FTLD) consists of a group of neurodegenerative diseases characterized by behavioural and executive impairment, language disorders and motor dysfunction. About 20-30% of cases are inherited in a dominant manner. Mutations in the microtubule-associated protein tau gene (MAPT) cause frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17T). Here we report a novel MAPT mutation (K298E) in exon 10 in a patient with FTDP-17T. Neuropathological studies of post-mortem brain showed widespread neuronal loss and gliosis and abundant deposition of hyperphosphorylated tau in neurons and glia. Molecular studies demonstrated that the K298E mutation affects both protein function and alternative mRNA splicing. Fibroblasts from a skin biopsy of the proband taken at post-mortem were directly induced into neurons (iNs) and expressed both 3-repeat and 4-repeat tau isoforms. As well as contributing new knowledge on MAPT mutations in FTDP-17T, this is the first example of the successful generation of iNs from skin cells retrieved post-mortem.

Incidence of amyotrophic lateral sclerosis in Europe

BACKGROUND

Geographical differences in the incidence of amyotrophic lateral sclerosis (ALS) have been reported in the literature but comparisons across previous studies are limited by different methods in case ascertainment and by the relatively small size of the studied populations. To address these issues, the authors undertook a pooled analysis of European population based ALS registries.

METHODS

All new incident ALS cases in subjects aged 18 years old and older were identified prospectively in six population based registries in three European countries (Ireland, UK and Italy) in the 2 year period 1998-1999, with a reference population of almost 24 million.

RESULTS

Based on 1028 identified incident cases, the crude annual incidence rate of ALS in the general European population was 2.16 per 100 000 person years; 95% CI 2.0 to 2.3), with similar incidence rates across all registries. The incidence was higher among men (3.0 per 100 000 person years; 95% CI 2.8 to 3.3) than among women (2.4 per 100 000 person years; 95% CI 2.2 to 2.6). Spinal onset ALS was more common among men compared with women, particularly in the 70-80 year age group. Disease occurrence decreased rapidly after 80 years of age.

CONCLUSIONS

ALS incidence is homogeneous across Europe. Sex differences in incidence may be explained by the higher incidence of spinal onset ALS among men, and the age related disease pattern suggests that ALS occurs within a susceptible group within the population rather than being a disease of ageing.

Cause of death and clinical grading criteria in a cohort of amyotrophic lateral sclerosis cases undergoing autopsy from the Scottish Motor Neurone Disease Register

BACKGROUND

The Scottish Motor Neurone Disease Register is a population based register of amyotrophic lateral sclerosis/motor neurone disease (ALS/MND) in Scotland, with high case ascertainment levels.

OBJECTIVE

To investigate the cause of death by autopsy and assess grading criteria in a cohort of cases of ALS from the Scottish MND Register.

METHODS

The records of 44 patients undergoing autopsy were reviewed to determine the cause of death, clinical assessment (El Escorial and modified World Federation of Neurology criteria) during life and neuropathological autopsy findings.

RESULTS

In a cohort of 44 cases undergoing autopsy between 1989 and 1998, the cause of death could be directly or indirectly (bronchopneumonia, aspiration/pneumonia and respiratory failure) attributed to MND in 32/44 (73%) cases. The clinical diagnosis of MND was confirmed at autopsy in 44/44 (100%) cases, 3/44 (7%) cases showed coexistent neurodegenerative disease and 5/44 (11%) were familial MND cases.

CONCLUSIONS

Within our cohort, MND contributes to death in the majority of cases and there is excellent clinicopathological correlation, irrespective of the clinical grading criteria used. However, the autopsy rate is low (4%) and further larger studies are required to identify heterogeneity within the disease.

50bp deletion in the promoter for superoxide dismutase 1 (SOD1) reduces SOD1 expression in vitro and may correlate with increased age of onset of sporadic amyotrophic lateral sclerosis

The objective was to test the hypothesis that a described association between homozygosity for a 50bp deletion in the SOD1 promoter 1684bp upstream of the SOD1 ATG and an increased age of onset in SALS can be replicated in additional SALS and control sample sets from other populations. Our second objective was to examine whether this deletion attenuates expression of the SOD1 gene. Genomic DNA from more than 1200 SALS cases from Ireland, Scotland, Quebec and the USA was genotyped for the 50bp SOD1 promoter deletion. Reporter gene expression analysis, electrophoretic mobility shift assays and chromatin immunoprecipitation studies were utilized to examine the functional effects of the deletion. The genetic association for homozygosity for the promoter deletion with an increased age of symptom onset was confirmed overall in this further study (p=0.032), although it was only statistically significant in the Irish subset, and remained highly significant in the combined set of all cohorts (p=0.001). Functional studies demonstrated that this polymorphism reduces the activity of the SOD1 promoter by approximately 50%. In addition we revealed that the transcription factor SP1 binds within the 50bp deletion region in vitro and in vivo. Our findings suggest the hypothesis that this deletion reduces expression of the SOD1 gene and that levels of the SOD1 protein may modify the phenotype of SALS within selected populations.

Descriptive epidemiology of amyotrophic lateral sclerosis: new evidence and unsolved issues

Amyotrophic lateral sclerosis (ALS) is a relatively rare disease with a reported population incidence of between 1.5 and 2.5 per 100,000 per year. Over the past 10 years, the design of ALS epidemiological studies has evolved to focus on a prospective, population based methodology, employing the El Escorial criteria and multiple sources of data to ensure complete case ascertainment. Five such studies, based in Europe and North America, have been published and show remarkably consistent incidence figures among their respective Caucasian populations. Population based studies have been useful in defining clinical characteristics and prognostic indicators in ALS. However, many epidemiological questions remain that cannot be resolved by any of the existing population based datasets. The working hypotheses is that ALS, like other chronic diseases, is a complex genetic condition, and the relative contributions of individual environmental and genetic factors are likely to be relatively small. Larger studies are required to characterise risks and identify subpopulations that might be suitable for further study. This current paper outlines the contribution of the various population based registers, identifies the limitations of the existing datasets and proposes a mechanism to improve the future design and output of descriptive epidemiological studies.

The incidence of motor nueron disease in Scotland

Between 1989 and 1998, 1226 cases of ALS/MND were identified in Scotland, with mean age of onset 65.2 (SD 11.9) years for men and 67.2 (SD 11.0) for women. Annual standardized incidence was 2.40 per 100,000 (95% CI 2.22-2.58). Using capture recapture methods we confirm a high level of case ascertainment for each year of study. Incidence and ascertainment of ALS has remained stable in a large population over a prolonged period of time. Large population-based databases can be used to test aetiological hypotheses.

A population based study of respiratory function in motor neuron disease patients living in Tayside and North East Fife, Scotland

Respiratory failure is a major cause of morbidity and the principal cause of death in motor neuron disease; non-invasive ventilation is increasingly used worldwide to palliate the respiratory symptoms. This observational study was designed to evaluate the prevalence of respiratory insufficiency within the motor neuron disease population of Tayside and North East Fife, Scotland. Twenty-six patients were identified, their diagnosis confirmed according to agreed criteria and subjected to the Revised Amyotrophic Lateral Sclerosis Functional Rating Scale, the Epworth Sleepiness questionnaire; spirometry, sniff nasal inspiratory pressure and nocturnal pulse oximetry measurements.Twenty-two (84.6%) patients reported one or more symptoms of respiratory insufficiency, 19 patients (73%) had forced vital capacity <80% of predicted in the sitting position and 10 (38.5%) had oxygen saturation <90% for >5% of night. On this basis a potential 10 patients required consideration for ventilation. As well as probable improvement in quality of life and survival for those patients this potential increase in workload has major educational, management and resource implications for health care providers.

Multiple sclerosis in Tayside, Scotland: detection of clusters using a spatial scan statistic

Debate continues over the relative importance of genetic factors over infectious agents in the aetiology of multiple sclerosis (MS). Detection of clusters of MS in space and time in the Tayside region of Scotland, UK would provide valuable evidence for the movement of infectious agents into a genetically susceptible population. A spatial scan statistic was used to detect, locate and provide a robust statistical test of any clusters found, without prior knowledge of their location or size. This was applied to a population-based MS register for the Tayside region of Scotland from 1970 to 1997, allowing for age at symptom onset, gender, population density and social deprivation. There were a total of 772 cases during the study period; an annual incidence of 72 per 100000. The mean age of symptom onset was 35.7 (SD = 10.5) and 73.8% of cases were women. There was a general increase in cases over time probably reflecting gradually better detection and diagnosis. There was a peak around the mid-1990s and some evidence of periodicity. There was a highly significant temporal cluster between 1982 and 1995 (P = 0.002) for the whole region. Additionally, a significant spatial cluster for the time period 1993-1995 was found centred in the rural area south-west of Perth (P=0.016). Significant temporal and spatial-temporal clusters are consistent with exogenous factors contributing to the distribution of MS in Tayside, Scotland.

Unexpected decline in survival from amyotrophic lateral sclerosis/motor neurone disease

OBJECTIVES

To describe survival of 1226 Scottish adults with amyotrophic lateral sclerosis/motor neurone disease (ALS/MND).

METHODS

Ten year, prospective, population based disease register. Cox time dependent proportional hazards modelling for multivariate survival analyses.

RESULTS

Median survival from onset was 25 months (interquartile range 16-34 months). In multivariate models we found an increased hazard with more recently diagnosed cases-that is, there was an unexpected decline in survival over the 10 year period (hazard ratio (HR) 1.06 (95% CI 1.04 to 1.09). Positive effects on survival were demonstrated for longer time from onset to diagnosis (HR 0.38 (95% CI 0.33 to 0.42), assessment by a neurological specialist (HR 0.56 (95% CI 0.40 to 0.77), and treatment with riluzole (HR 0.24 (95% CI 0.14 to 0.42). Poor prognosis was associated with bulbar onset (HR 1.25 (95% CI 1.09 to 1.46) and a mixed lower and upper motor neurone syndrome (HR 1.23 (95% CI 1.01-1.49) and increasing age.

CONCLUSIONS

We found an unexpected decline in survival over the 10 year period, despite controlling for potential confounding variables. We would be cautious about over-interpreting these observations and suggest that further research is required to confirm or refute these findings.

Frequency, timing and outcome of gastrostomy tubes for amyotrophic lateral sclerosis/motor neurone disease--a record linkage study from the Scottish Motor Neurone Disease Register

AIMS

To describe the frequency, timing and outcome from gastrostomy in amyotrophic lateral sclerosis/motor neurone disease (ALS/MND).

METHODS

The Scottish MND Register, a population based disease register (1989-1998), with record linkage to the Scottish Morbidity 1 dataset of hospital discharges coded for gastrostomy procedure was used. Descriptive statistics of patients undergoing gastrostomy were extracted. Survival analysis used Kaplan Meier and Cox proportional hazards methods.

RESULTS

For patients diagnosed between 1989-98, 142 percutaneous endoscopic gastrostomy (PEG) insertion episodes were identified in 1226 patients, 130 of which occurred before the censoring date of 31 December 1999.Annually, on average, 5% of all revalent patients underwent gastrostomy, and this rate appeared to double between 1989-98. The cumulative incidence of gastrostomy was 11%. Mean age at PEG tube insertion was 66.8 years, with a mean disease duration of 24 months. Median survival from PEG tube insertion was 146 days. The 1 month mortality after gastrostomy was 25%. Gastrostomy did not confer a survival advantage compared with no gastrostomy.

CONCLUSIONS

We found that gastrostomy feeding tubes are being inserted more frequently in people with ALS/MND. An unexpectedly high early mortality was detected which probably reflects a lack of selection bias compared with previously published data. It is possible that changes in the practice of gastrostomy placement since 1998 result in better outcomes for patients with ALS/MND. Prospective studies are required to assess the risks and benefits of enteral nutrition in ALS/MND.

The epidemiology of amyotrophic lateral sclerosis (ALS/MND) in people aged 80 or over

OBJECTIVE

To describe the clinical features, incidence, survival and process of care of people with Amyotrophic Lateral Sclerosis/Motor Neurone Disease aged 80 years or more at diagnosis.

DESIGN

Prospective, population-based descriptive epidemiological study.

SETTING

Scotland (population 5.1 million), The Scottish Motor Neurone Disease Register 1989-1998.

PARTICIPANTS

135 people aged 80 years or over at diagnosis.

METHODS

Descriptive Epidemiology of Amyotrophic Lateral Sclerosis/Motor Neurone Disease in the over 80s. Survival described using Kaplan-Meier curves.

RESULTS

135 of 1226 cases (11%) were aged 80 years or more. Sixty-seven (50%) had bulbar onset, and 58 (43%) were men. The standardised incidence was 10.2/100000 (95% CI 7.4-13.1) in men and 6.1/100000 (95% CI = 4.3-7.6) in women. Median survival from first symptoms was 1.7 years (IQR 1.0-2.8), less than younger patients (P = 0.0003; log Rank test). We found evidence of differences in the process of care, as older people were less likely to be prescribed Riluzole (OR 0.12, 95% CI = 0.02-0.89) or be assessed by a neurologist (OR 0.76, 95% CI = 0.67-0.86).

CONCLUSION

This is the first comprehensive report of the epidemiology of Amyotrophic Lateral Sclerosis/Motor Neurone Disease in older people. Clinical presentation and survival differ from the population as a whole. There is evidence of a different process of care. While this may be to the detriment of their survival, this finding would need to be confirmed by further prospective studies.

Rapid mutation detection by the transgenomic wave analyser DHPLC identifies MYOC mutations in patients with ocular hypertension and/or open angle glaucoma

AIMS

To rapidly screen Scottish patients with a family history of open angle glaucoma (OAG) or ocular hypertension (OHT) for mutations in the myocilin gene (MYOC) and develop a new rapid screening method for MYOC mutation detection.

METHODS

All three exons of the MYOC gene were amplified by PCR from genomic DNA and subjected to direct DNA sequencing. Mutation detection methodology was also developed based on denaturing high performance liquid chromatography (DHPLC). A recurrent mutation was investigated by analysis of microsatellite haplotypes at the MYOC gene locus.

RESULTS

Mutations were identified by DNA sequencing in four families. MYOC mutation Q368X was found in three kindreds and the fourth family carried the mutation G367R. The Q368X mutation was found to be associated with the same haplotype for markers closely flanking the MYOC gene. The mutations were identified by direct sequencing and were also readily detected by DHPLC analysis of PCR fragments, demonstrating that this is a robust method for MYOC analysis in future.

CONCLUSIONS

Mutations in the MYOC gene were identified in patients presenting with highly variable phenotypes from normal through OHT to severe OAG. Haplotype analysis showed that mutation Q368X is likely to be an ancestral mutation in this population. DHPLC analysis is an accurate, rapid and cost effective method for MYOC mutation analysis in large population samples.

Are the El Escorial and Revised El Escorial criteria for ALS reproducible? A study of inter-observer agreement

INTRODUCTION

For accurate diagnosis, inter-observer agreement of criteria is important.

METHODS

Using case records, the reproducibility of the original and revised El Escorial diagnostic criteria for amyotrophic lateral sclerosis were tested in a consecutive series of people referred to the Scottish Motor Neuron Disease Register.

RESULTS

Agreement between independent observers was similar (weighted kappa: 0.783, 95% CI 0.656 to 0.911 (original criteria), 0.681, 95% CI 0.485 to 0.878 (revised)).

CONCLUSIONS

Serious errors are unlikely, but the revised criteria may be less reproducible as they include more diagnostic categories. Revisions of diagnostic criteria should be tested for reproducibility and validity prior to widespread adoption.

Motor neuron disease--a review

It is now clear that patients with MND are best managed using a multi-disciplinary approach conforming to evidence-based guidelines. Whilst scientific advances into the aetiology of MND have been of great importance in both the understanding of this and other neurodegenerative disease, they have only recently led to therapy directed at disease progression. The management of patients with MND remains largely supportive but it is hoped that the future may hold better prospects for those with the disease.

Population based cost utility study of interferon beta-1b in secondary progressive multiple sclerosis

OBJECTIVE

To evaluate the cost utility of interferon beta-1b in secondary progressive multiple sclerosis.

DESIGN

Population based cost utility model (healthcare perspective). Data on use of health services were obtained from case records and routine morbidity data and utility values from a EuroQol survey. Local and published costs were used. Effectiveness was modelled using data on relative risk reductions from a randomised trial of interferon beta-1b.

SETTING

Tayside region, 1993-5.

SUBJECTS

132 ambulatory people with secondary progressive multiple sclerosis.

MAIN OUTCOME MEASURES

Cost per quality adjusted life year (QALY) gained. Rate of relapse and proportion becoming wheelchair dependent over three years.

RESULTS

The number needed to treat for 30 months to delay time to wheelchair dependence in one person by nine months was 18 (95% confidence interval 5 to 26). For every 18 people treated for 30 months, six relapses would be prevented, gaining 0.397 discounted QALYs. The cost per QALY gained was 1 024 667 pounds sterling (276 466 pounds sterling to 485 499 pound sterling). If treatment was restricted to patients attending neurology services, the number needed to treat was 14 (cost per QALY gained 833 pounds sterling 514 (161 358 pounds sterling to infinity)). The cost per QALY gained was not sensitive to changes in cost which took account of a societal perspective.

CONCLUSIONS

The cost per QALY gained from interferon beta is high because of the high drug cost and modest clinical effect. Resources could be used more efficiently elsewhere.

The prevalence of multiple sclerosis in Tayside, Scotland: do latitudinal gradients really exist?

To determine the prevalence of multiple sclerosis (MS) in the Tayside Health Board Area, Scotland, we carried out a population-based survey using four intersecting sources (Neurology Department records, a survey of general practitioners, Scottish Morbidity Records of discharges from hospitals and visual evoked response requests). A two-source capture-recapture model estimated survey coverage, and direct age-sex standardisation was used to take account of different population structures. Comparisons were made between the prevalence in Scotland and that in the rest of the United Kingdom. A total of 727 (definite and probable) and 880 cases (early, probable and possible) were identified using the criteria of Poser et al. and those of Allison and Millar in a population of 395,600 (1995 mid-year estimate). The prevalence of MS on 1 September 1996 was 184/100,000 (95% confidence interval 171-198) and 222/100,000 (95% confidence interval 210-240), respectively. The two-source capture-recapture model estimated that the survey was between 93% and 99% complete. Age-sex standardisation eliminated certain north-south differences in prevalence when comparisons were made with previous surveys. Diagnostic misclassification may also have influenced reported prevalence statistics. The prevalence is similar to that found in revised figures from the Grampian region in Scotland but significantly higher than recent estimates from England and Wales. Methodological differences may account for most of the reported differences between north and south, although there is still evidence to suggest that MS is more prevalent in northern Great Britain and Northern Ireland than in England and Wales.

Molecular genetic analysis of the APEX nuclease gene in amyotrophic lateral sclerosis

We analyzed genomic DNA from ALS patients for mutations in the apurinic/apyrimidinic endonuclease (APEX nuclease) gene. We identified three rare polymorphisms in the untranslated region of the gene and one common two-allele polymorphism (D148E). The allelic frequency D148E was significantly different in sporadic ALS patients compared with controls. A conserved amino acid change and a 4-base pair deletion were also identified in sporadic ALS patients. These data suggest that APEX nuclease may contribute to the etiology of ALS.

Estimating the prevalence of multiple sclerosis in the United Kingdom by using capture-recapture methodology

The geographic distribution of multiple sclerosis is nonrandom, as the disease is more prevalent in temperate than in tropical regions. Surveys conducted between 1970 and 1996 suggest that multiple sclerosis is more prevalent in the northern part of the United Kingdom than in the southern part. This north-south gradient ("the latitudinal gradient") might be a methodological artifact, because high prevalence figures from serial surveys of the northern part of the United Kingdom might have been the result of better ascertainment. By using capture-recapture methods, the authors found that case ascertainment was similar in the northern and southern parts of the United Kingdom. When prevalence figures for multiple sclerosis in the southern United Kingdom were increased to account for the number of unobserved cases, the difference persisted: The prevalence of multiple sclerosis in the northern part of the United Kingdom appeared to be at least 180 cases per 100,000 persons, whereas the maximum prevalence in the southern part of the United Kingdom was less than 160 cases per 100,000 persons. The distribution of multiple sclerosis in the United Kingdom is not uniform and is consistent with the hypothesis that populations with a high prevalence of multiple sclerosis may be genetically predisposed to the disease.

Avoiding false positive diagnoses of motor neuron disease: lessons from the Scottish Motor Neuron Disease Register

OBJECTIVES

To describe the frequency and characteristics of those patients initially registered with the Scottish Motor Neuron Disease Register (SMNDR) but who subsequently had a diagnosis other than MND made (false positives), to analyse the features which led to a revised diagnosis, and to draw conclusions which might improve routine neurological practice.

METHODS

The Scottish Motor Neuron Disease Register is a community based, prospective disease register to identify and follow up all incident cases of motor neuron disease in Scotland. Fifty three patients out of a total of 552 registered are presented, who, after initial registration, were later excluded because they failed to satisfy the register's diagnostic criteria.

RESULTS

Seven of these patients were labelled as "MND plus" syndromes and may represent a distinct subset of MND. The remaining 46 patients had an alternative diagnosis made (false positive group), accounting for 8% of the total. In half of these cases, potentially beneficial therapies are available. The predominant reasons which lead to a diagnostic revision were: failure of symptom progression, development of atypical clinical features for MND, and investigation results.

CONCLUSIONS

Patients with MND should undergo thorough and relevant investigations at presentation with the emphasis on neuroradiological imaging and neurophysiology; all patients should be followed up by an experienced neurologist, particularly those in whom symptoms and signs are restricted to either the bulbar or spinal muscles; failure of symptom progression or development of atypical features should lead to an early reassessment; finally, patients should be informed of the diagnosis only when it is secure.

Superoxide dismutase mutations in an unselected cohort of Scottish amyotrophic lateral sclerosis patients

Mutations in the Cu/Zn superoxide dismutase (SOD1) gene are responsible for some cases of familial amyotrophic lateral sclerosis (ALS). We have shown that SOD1 mutations can also occur in apparently sporadic ALS. To establish how often this happens we have undertaken a study of the prevalence of SOD1 mutations in an unselected cohort of Scottish ALS patients, with both sporadic (n = 57) and familial (n = 10) disease. Single strand conformation polymorphism analysis was used to scan for new mutations, and selective restriction enzyme digestion to screen for 11 of the 20 SOD1 mutations published to date. We detected mutations in five (50%) of the familial ALS patients and also in four (7%) of the sporadic patients. One mutation, ile113thr, seems to be particularly prevalent in the Scottish population since it was detected in a total of 6/67 (9%) unrelated cases.

Clinical heterogeneity of familial motor neuron disease: report of 11 pedigrees from a population based study in Scotland. The Scottish Motor Neuron Disease Research Group

Five percent of incident patients with MND in Scotland 1989-1990 had a family history of this disease. This paper assesses the demographic and clinical features of this group.

The cost of epilepsy in patients attending a specialist epilepsy service

Epilepsy is a common disability, especially in young adults, and, as the costs to the community are likely to be high, estimates are required to plan health and community care. The neurological unit of Dundee Royal Infirmary provides an epilepsy clinic for the Tayside region (population 300,000) and in 1991 the records of over 303 patients were computerized using the Epicare system developed by Sanofi-Winthrop. It was calculated that the total state expenditure on care was 662,919 pounds (2188 pounds/head) in 1991. The direct health costs were obtained by reviewing database entries and medical records and were estimated to be 159,192 pounds (24%), including 77,171 pounds for drugs, 64,750 pounds for hospital care and 17,271 pounds for general practice consultations. The cost of welfare payments was 503,728 pounds/year (76%) (4419 pounds/recipient). The transfer payments to patients with epilepsy greatly exceed the costs of health care and any management strategy which improves the prospects for employment and independence of people with epilepsy is likely to produce significant fiscal benefits for both the individual and the state.

Maternally transmitted partial direct tandem duplication of mitochondrial DNA associated with diabetes mellitus

Mitochondrial DNA from a 38 year old male with diabetes mellitus and features of mitochondrial dysfunction was analysed and shown to include a population with a partial duplication. The partially duplicated mitochondrial DNA molecules were evident in both muscle and blood. The region of mitochondrial DNA duplicated includes the origin of heavy strand replication, but not the light strand origin. This patient has features in common with other cases of partial direct tandem duplications and with a family which was reported to harbour a 10.4 kb mtDNA deletion. Initial restriction enzyme analysis of our case produced results consistent with a partial deletion of mitochondrial DNA. This leads us to propose that the rarity of reports of partial mitochondrial DNA duplications may stem in part from the classification of such mutants as partial deletions.

The prognosis of adult-onset motor neuron disease: a prospective study based on the Scottish Motor Neuron Disease Register

The Scottish Motor Neuron Disease Register (SMNDR) is a prospective, collaborative, population-based project which has been collecting data on incident patients since 1989. In this report we present the clinical features of 229 patients with motor neuron disease (218 sporadic and 11 familial) diagnosed in 1989 and 1990 and compare their prognosis with previous studies of survival. The overall 50% survival from symptom onset was 2.5 years (95% CI, 2.2-3.0) and 5-year survival 28% (95% CI, 20-36%). The presence of progressive bulbar palsy (PBP), either at presentation or developing during the course of the illness, significantly reduced survival and was the most important prognostic indicator. Patients who survived longer than 5 years from symptom onset did not have PBP as part of their presenting illness. The prognosis was worse for women, and this was in part related to the higher frequency of PBP in older women, but age was also an independent adverse risk factor. Differences in survival between this and previous series can probably be explained on the basis of variation in case definition and ascertainment methods.

Utility of Scottish morbidity and mortality data for epidemiological studies of motor neuron disease

OBJECTIVES

To determine the accuracy of (1) hospital discharge data and (2) death certificates, coded as motor neuron disease (MND).

DESIGN

Comparison of data from The Scottish Motor Neuron Disease Register (SMNDR) with routinely collected Scottish Hospital In-Patient Statistics (SHIPS) and death certificate coding.

SETTING

Scotland UK.

PATIENTS

1) 379 adults (> 15 years) discharged for the first time from a Scottish hospital in 1989-90 and (2) 281 deaths in the same period assigned to the International Classification of Diseases (ICD)-9, category 335 (MND).

MAIN OUTCOME MEASURES

The sensitivity and positive predictive value of a diagnosis of MND as retrieved by (1) the Information and Statistics Division of the Common Services Agency for the Scottish Health Service for morbidity data and (2) the Registrar General's office for mortality data, using the SMNDR as the 'gold standard'.

RESULTS

(1) Thirty per cent of adult patients identified as having MND by SHIPS did not have this disease and 23% of patients with MND did not appear on SHIPS. The sensitivity of a diagnosis of MND, as retrieved by SHIPS, was 84% and the positive predictive value was 70% overall. Miscoding of patients with pseudobulbar palsy caused by cerebrovascular disease was the major source of false positive error. The incidence of adult onset sporadic MND was over estimated by SHIPS by a factor of 1.6. (2) Mortality data were more accurate, with a false negative rate of 6% and a positive predictive value of 90%.

CONCLUSIONS

Coded hospital discharge data are an inaccurate record of a diagnosis of MND and cannot, in their present form, be used as a reliable measure of disease incidence in Scotland. Greater care is required in the preparation of discharge summaries and coding if these data are to be useful for health care planning and epidemiological research. SHIPS is, however, an important source of information to achieve a complete sample of patients with MND. There is also a problematic false positive rate for mortality data but this source more closely approximates true incidence.

Multiple sclerosis and blood transfusion

It has recently been suggested that multiple sclerosis (MS) may be triggered by a retrovirally encoded superantigen. If true, then MS should be associated with risk factors that predispose to retroviral infection. Blood transfusions represent one such risk factor. 150 Scottish patients with 'clinically definite' or 'probable' MS and 150 age-/sex-matched neurological controls were questioned about blood transfusion. 7 (4.7%) of the patients and an equal number of controls had received a blood transfusion before the year of disease onset in the matched case (odds ratio 1.0, 95% C.I. 0.3-3.34). These results provide no evidence that blood transfusion is associated with an increased risk of MS.

Motor neuron disease and polio in Scotland

An analysis of mortality and morbidity rates for motor neuron disease (MND) in Scotland has confirmed earlier observations that the disease is more common in men and older age groups. The geographical distribution is non-uniform and related to discharge rates for all neurological diseases. Discharge and mortality rates are increasing but there has been no decline in populations who would have been vaccinated against polio.

Western blotting analysis in patients with MS using human brain vessels as antigen

Serum samples from patients suffering from multiple sclerosis, other neurological diseases and normal controls were screened by "western blotting" for antibody directed against proteins of human brain vessels purified from a post mortem brain. A small number of sera contained autoantibodies against some of the proteins of the brain vessels, particularly in patients suffering from MS, epilepsy and migraine. The significance of these results is discussed.

The morbidity of multiple sclerosis

Although the clinical course of multiple sclerosis is benign in up to one-third of patients, it is important to recognize the high rate of morbidity in others. Most individuals pass through a remitting phase but in a significant proportion the clinical manifestations subsequently recur, persist or slowly progress, and disability accumulates with time. Here we describe the frequency and spectrum of morbidity in a population based cohort of patients with multiple sclerosis. These statistics will guide those providing health care resources and planning services for patients with multiple sclerosis.

Features of multiple sclerosis in older patients in South Wales

Multiple sclerosis (MS) may occur outside the commonly accepted age range. Data relating to features of MS in a population in South Wales have been analysed to find features which characterise older patients. The older patients are more severely disabled due to the accumulation of visual defects and motor signs and symptoms. The course of the disease is marked by single localised attacks with long remissions. Those with onset over 50 years deteriorate more rapidly, but in those who were over 50 at the time of interview, this did not occur. It is suggested that there is no essential difference in MS in older patients, but there may be features which reflect normal ageing and diseases commoner in old age.