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Biomedical subjects

M C Downer

Publications and source records attributed to M C Downer.

At least 19 recordsLinked to original sources
PubMed2000

Is alcohol responsible for more intra-oral cancer?

The role of the major risk factors, tobacco smoking and alcohol consumption, on trends in intra-oral cancer mortality in England and Wales between 1911 and 1990 was investigated, using lung cancer and liver cirrhosis as surrogate markers for smoking and drinking. Standardised mortality data on lung cancer and liver cirrhosis from the Office of Population Censuses and Surveys, aggregated into 5-year time periods for ages 35-64 and 65+ years, were regressed on corresponding data for intra-oral cancer. The strongest associations were in males aged 35-64 with a high negative correlation between lung and intra-oral cancer (rho=-0.98, 95% CI -0.99 to -0.96, P<0. 01) and, conversely, a positive correlation between liver cirrhosis and intra-oral cancer (rho=0.71, 95% CI 0.34 to 0.89, P<0.01). The findings suggest that rising alcohol consumption since the 1950s is more closely related to increasing intra-oral cancer incidence and mortality than smoking, most notably among younger males since the early 1970s.

Adult↗
PubMed2000

Optimum bitewing examination recall intervals assessed by computer simulation.

OBJECTIVE: To assess the effect of altering bitewing examination recall intervals on health gain from dental restorative treatment and to determine optimum recall intervals under varying clinical conditions. DESIGN: A computer simulation of the caries process in posterior approximal tooth surfaces. The effect of superimposing restorative treatment, based on diagnoses from bitewing radiological examinations carried out at differing time intervals, was incorporated. Input data included caries attack rates, median survival times of restorations, and sensitivity (Sn) and specificity (Sp) of treatment decision making by a high (A) and a low (B) performing dentist. PARTICIPANTS: A hypothetical population, initially 14-15 years old. INTERVENTIONS: Class II amalgam restorations. OUTCOME: Health gain in utility based units (UBUs) was assessed relative to interim end point UBUs pertaining under 'do nothing scenarios'. RESULTS: One thousand approximal surfaces, designated initially as 920 sound, 51 carious and 29 filled were followed in the model over 10 years. The greatest health gain (39.33 UBUs) was from dentist A (Sn = 0.23, Sp = 0.99, restoration median survival time = 20 years, caries rate = 4.4% per annum, optimal recall interval between bitewing radiological examinations = 7 months). The least was from dentist B (Sn = 0.52, Sp = 0.88, median survival time = 5 years. caries rate = 0.0% per annum, optimal recall interval between bitewing radiological examinations > 120 months) representing a loss of 16.79 UBUs compared with 'do nothing'. CONCLUSIONS: In the best interests of their patients, it would seem that dentists need to exercise considerable caution in making positive decisions to restore approximal tooth surfaces on the basis of bitewing radiographic evidence and that for some dentists current guidelines for bitewing examination intervals would appear to be too permissive.

Computer Simulation↗
PubMed2000

The temporal and spatial epidemiology of lip cancer in England and Wales.

OBJECTIVE: To examine trends in lip cancer mortality and incidence during the 20th century, and its geographical distribution, in England and Wales as a prerequisite to establishing any essential differences in the aetiology of lip and intra-oral cancer. METHOD: Age-standardised rates for lip cancer mortality by gender from 1901 to 1991 were derived from archived OPCS data. Standardised incidence rates from 1962 to 1986 were also calculated. Registrations of lip cancer between 1979 and 1983 in the 15 RHAs covering England and Wales were obtained from the same source and standardised incidence ratios (SIR) computed. RESULTS: Progressive and sustained falls in lip cancer mortality and incidence were recorded in the period covered. In males, these related particularly to cohorts born after 1856. In addition, the incidence of lip cancer in both genders was found to be raised in a band stretching from East Anglia to the South West and also in the Trent and Wales RHAs. CONCLUSIONS: The findings support an hypothesis that employment in the agriculture, forestry and fishing industries, and also pipe smoking, were the major risk factors for lip cancer in the 20th century. Further research is required to differentiate between the aetiological risk factors for lip and intra-oral cancer.

Adult↗
PubMed2000

The association between intra-oral cancer and surrogate markers of smoking and alcohol consumption.

OBJECTIVES: 1) To describe the relationships between intra-oral cancer incidence, in England and Wales and the corresponding incidence of lung cancer (a surrogate for cigarette smoking), and liver cirrhosis mortality (a surrogate for alcohol consumption). 2) To elucidate the role and relative importance of cigarette smoking and alcohol consumption in the aetiology of intra-oral cancer. METHOD: Registration data for intra-oral cancer in males and females aged 35 years and over for the 15 regional health authorities (RHAs) in England and Wales in 1979-1983 were obtained from the Office of Population Censuses and Surveys and aggregated for the five-year period. Census-based population data enabled standardised incidence ratios (SIR) to be calculated for each RHA. Using the identical method. SIRs were also computed for lung cancer and standardised mortality ratios (SMR) for liver cirrhosis, the latter for the period 1974-1978 to reflect the shorter induction time for liver disease than for cancer. Correlation coefficients (Spearman's rho) were calculated between the surrogate measures and intra-oral cancer incidence. RESULTS: For all three diseases a north-south gradient, favouring the more southerly RHAs was generally apparent. For males, the correlation between liver cirrhosis mortality and intra-oral cancer incidence was greater and statistically more significant (rho=0.75, P<0.01) than that between lung and intra-oral cancer incidence (rho = 0.63, P<0.05). For females, the corresponding correlation coefficients were positive but not significant. CONCLUSION: For males at least, the association between a surrogate marker for alcohol consumption and intra-oral cancer was greater than that observed for cigarette smoking. This adds further evidence to the current view that alcohol consumption may be more important in the aetiology of intra-oral cancer than cigarette smoking.

Adult↗
PubMed1999

How long do routine dental restorations last? A systematic review.

OBJECTIVE: To conduct a systematic review of the literature on the longevity of routine dental restorations in permanent posterior teeth, and to identify and examine factors influencing its variability. METHOD: Accepted guidelines were followed. An advisory group oversaw the project. Simple Class I and Class II amalgam, composite resin, glass ionomer and cast gold restorations were covered. Comprehensive searching of electronic databases, hand-searching, and location of 'grey' literature, generated 124 research reports. Those considered relevant were assessed for validity and quality according to agreed criteria. The analysis was descriptive. RESULTS: Eight of 58 relevant research reports were categorised, according to agreed criteria, as being of satisfactory validity and quality. They suggested that 50% of all restorations last 10 to 20 years, although both higher and lower median survival times were reported. The findings were supported by the totality of studies reviewed. However, variability was substantial. Restoration type, materials, the patient, the operator, the practice environment and type of care system appeared to influence longevity. CONCLUSIONS: Many studies were imperfect in design. Those considered to be the most appropriate for analysis were too limited to undertake a formal statistical exploration. Therefore there remains a need for definitive randomised controlled trials of restoration longevity, of sound design and adequate power, employing standardised assessments and appropriate methods of analysis.

Bicuspid↗
PubMed1999

Caries experience and sucrose availability: an analysis of the relationship in the United Kingdom over fifty years.

OBJECTIVE: A previous study suggested that the most likely explanation for the rise and subsequent fall in caries in children in England and Wales during the last 50 years was the concurrent increase and then reduction in the sugar challenge to the population, mitigated after the early 1970s by the preventive effect of fluoride toothpaste. The current objective was to quantify the relationship between sucrose available for consumption annually since 1948 and caries experience at 5 and 12 years. METHOD: In a retrospective, longitudinal ecological study, cross-sectional mean dmft values at 5 years and DMFT values at 12 years in England from 1948 to 1968 and England and Wales from 1973 to 1996/97, from three series of standardised surveys, were regressed on data for the relevant years on sucrose available for consumption in the UK. RESULTS: For sucrose consumption and 5-year-old dmft, Spearman's rho was +0.62 (P < 0.05) while for 12-year-old DMFT the value was +0.84 (P < 0.001). For the 12 year age group, Pearson's coefficient could also be calculated (r = +0.87; P < 0.001). CONCLUSION: For several reasons caution should be used in interpreting these findings. Nevertheless they do suggest a strong positive correlation over time between dmft/DMFT and sucrose availability nationally.

Child↗
PubMed1998

Health gain from restorative dental treatment evaluated by computer simulation.

OBJECTIVE: To simulate the influence over time of relevant factors on health gain from restorative dental treatment under varying assumptions and to compare outcomes with those resulting under a 'do nothing' scenario. DESIGN: A decision model was used in a computer simulation of the caries process in posterior approximal tooth surfaces. The effect of superimposing restorative treatment, based on bitewing radiology, was incorporated. Input data came from current observational studies and included caries progression rates, notional survival times of restorations, and sensitivity (Sn) and specificity (Sp) of treatment decision making by a high (A) and a low (B) performing dentist. Utility values, on a scale 0-1, for different tooth health states were obtained from questioning 92 adults of appropriate age. SETTING: By assumption, the primary dental care sector. PARTICIPANTS: A hypothetical population, initially 14-15 years old. INTERVENTIONS: Class II amalgam restorations. OUTCOME: Computed in utility based units (UBUs) as sums of the product of numbers of sound, carious and restored surfaces and their utility values. Health gain (in UBUs) was assessed relative to interim end point UBUs pertaining under 'do nothing'. RESULTS: One thousand approximal surfaces, designated initially as 920 sound, 51 carious and 29 filled were followed in the model over 10 years. The greatest health gain (33.16 UBUs) was from dentist A (Sn = 0.23, Sp = 0.99, 50 per cent restoration survival rate = 10 years, caries rate = 4.4% per annum). The least was from dentist B (Sn = 0.52, Sp = 0.88, 50% survival = 5 years, caries rate = 0.0% per annum) representing a loss of 17.07 UBUs compared with 'do nothing'. CONCLUSIONS: Results suggest that caution is advisable when making positive decisions to restore on the basis of bitewing radiographs.

Adolescent↗
PubMed1998

An interim determination of health gain from oral cancer and precancer screening: 3. Preselecting high risk individuals.

OBJECTIVE: To perform a sensitivity analysis using a decision model for simulating opportunistic screening for oral cancer and precancer in order to obtain an estimate of health gain from screening high risk dental patients, identified with the aid of artificial intelligence. DESIGN: A hypothetical opportunistic screening programme based on preselection of high risk patients was compared with screening all eligible patients and with a 'do nothing' scenario. The basic assumptions and data used in the model have been described previously. SETTING: Screening would be carried out in dental practices. PARTICIPANTS: A notional population of 100,000 adults of average age 55 years and 20 years life expectancy. INTERVENTIONS: Systematic clinical examination of the oral mucosa of high risk individuals identified by artificial intelligence on the basis of personal characteristics and life style. OUTCOME MEASURES: QALYs and equivalent lives saved RESULTS: The following estimates of health gain were obtained: the preselected screened group (n = 25,000) would achieve 1,993,294 QALYs. Without preselection, screening an unselected population of 100,000 eligible adults would result in 1,993,094 QALYs. Under the 'do nothing' scenario, 100,000 unscreened individuals would achieve 1,992,982 QALYs. Selective screening could avoid the equivalent of 15 deaths per 100,000 subjects examined. Screening preselected subjects at heightened risk would save the equivalent of two to three times the number of healthy lives compared with non-selective screening. Only one quarter of the population would need to be examined. CONCLUSIONS: Opportunistic screening of preselected dental patients for oral cancer and precancer appears to be a promising health promotion strategy and should be subject to formal economic appraisal.

Cost-Benefit Analysis↗
PubMed1997

An interim determination of health gain from oral cancer and precancer screening: 1. Obtaining health state utilities.

OBJECTIVE: To obtain preliminary health state utility values for oral precancer, and stage 1 and stage 2 (or greater) oral cancer, for use in a study involving quality of life measurement. DESIGN: Members of the general public were personally interviewed and asked to complete a standard gamble questionnaire in which each individual had to choose between having oral cancer or precancer (a description of each stage and its treatment was given), and being perfectly healthy but with a probability (p) from 0 to 1, of immediate death. There were three questions, the first related to a state of oral precancer, the second to a small cancer (< 2 cm) and the third to a large oral cancer (> 2 cm). The utility of each state was equal to the probability that the subject would opt for having the disease (1-p). The pooled responses of all subjects were analysed using a Wilcoxon matched-pairs signed-ranks test. SETTING: The premises of a commercial company. PARTICIPANTS: A convenience, quota sample of 100 employees aged 40 years or over. RESULTS: The mean utility values obtained were: oral precancer = 0.92; small oral cancer = 0.88; large oral cancer = 0.68. There was a significant difference between all three states (P < 0.05). CONCLUSIONS: The study relied on a convenience sample to elicit the public's perceptions of different oral cancer states. Nevertheless, despite this limitation, it was considered that the utility values derived were suitable for incorporation in measurements of quality adjusted life years.

Adult↗
PubMed1997

An interim determination of health gain from oral cancer and precancer screening: 2. Developing a model of population screening.

OBJECTIVE: To design a simulation model of population screening for oral cancer and precancer and to obtain estimates of quality adjusted life years (QALYs) and lives gained from screening, using decision analysis. DESIGN: A hypothetical opportunistic screening programme was compared with the status quo (no screening). Variables included in the model were attendance (50 per cent of the eligible population); prevalence of oral cancer (0.098 per cent) and precancer (2.57 per cent), positive (0.67) and negative (0.99) predictive values of screening, stage distribution of cancer (40 per cent stage 1, 60 per cent stage 2+ without screening; 60 per cent stage 1, 40 per cent stage 2+ with screening); average survival (precancer, 19.2 years; stage 1, 14.6 years; stage 2+, 10.8 years); and the public's perceived utilities of the various outcomes (health, 1.00; precancer, 0.92; stage 1 cancer, 0.88; stage 2+ cancer, 0.68). One cycle of the programme was modelled. SETTING: Screening would be carried out in dental practices. PARTICIPANTS: A notional population of 100,000 adults of average age 55 years and 20 years life expectancy entered each decision pathway (screening or status quo). INTERVENTIONS: Systematic clinical examination of the oral soft tissues. OUTCOME MEASURES: QALYs and equivalent lives saved. RESULTS: Assuming 50 per cent attended, the population offered screening achieved 1,993,094 QALYs. With no screening the corresponding end point was 1,992,982 QALYs. The gain from screening was therefore 56 QALYs representing an equivalent of 2.8 lives saved. CONCLUSIONS: Though a simplification, this model is likely to be more reliable than intuitive prediction and is amenable to sensitivity analysis of different screening strategies. A modest health gain from screening was predicted by the model.

Adult↗
PubMed1996

Oral health week.

This article reports on the Oral Health Week held in December 1994 and focuses on an initiative by the BDA which organised dentists and volunteers from Age Concern in a project to look at oral health for the elderly. It examines the aims and the results of the week and draws some useful conclusions on improving the outcome if a project such as this were attempted again.

Aged↗