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Time-series regression of successive aggregate data has been used widely to explore relationships between substance use and harm, or to measure effects of policy interventions. This paper suggests minimal standards to conduct such analyses with respect to validity and reliability of underlying data, statistical techniques and requirements and interpretation of results.
BACKGROUND: Reporting of a recent international comparison of cancer survival rates has left an impression of inadequate treatment of patients in the UK but failed to address adequately the extent to which differences in survival may reflect variation in the completeness and accuracy of cancer registration. The aim of this study was to quantify the extent to which differences in registration practice may confound comparisons of survival from cancer of the colon. METHODS: A cohort of incident cases of colon cancer identified from records held by the North Western Regional Cancer Registry was used to simulate the effects on survival of changes in clinical and registration factors. The survival curve produced after each simulation was compared with that for aggregated data from 21 European registries. RESULTS: The observed survival differences were not explained by more effective primary treatment or by misclassification of in situ cases as malignant disease, whereas the exclusion of cases with only a clinical diagnosis produced estimates close to those of the European cohort. CONCLUSION: The observed survival differentials may not be due to differences in the quality of care but may reflect the failure of some European registries to register all patients with advanced disease.
OBJECTIVE: The purpose of the present study was to report on caries status and to explore possible reasons for changes in caries experience among 5- and 12-year-old Norwegian children. DESIGN: National cross-sectional and time trend study. METHODS: Aggregated data from the Public Dental Services and from official statistics were used. Information was available on the total number of children, the proportion receiving treatment, sale of fluoride tablets, socio-economic background, caries prevalence and dmft/DMFT scores. RESULTS: The prevalence of caries among 5-year-olds reached a low of 30.4% in 1997 and increased to 38.9% in 2000. The mean dmft scores increased from 1.1 to 1.5. Conversely, the prevalence of caries among 12-year-olds decreased from 55.4% in 1997 to 52.2% in 2000 and the mean DMFT score from 1.7 to 1.5. Bivariate analyses at county level revealed significant associations, which for the most part disappeared in multivariate analyses. The sale of fluoride tablets had a significant effect on caries prevalence among 5-year-olds in 1998, in 1999 and in 2000. Infant mortality was associated with the dmft score in 1999. The only consistently significant predictor of caries experience at 12 years of age was caries prevalence at age 5. CONCLUSIONS: There has been a highly significant increase in caries experience among 5-year-olds (P < 0.001) and a levelling off among 12-year-olds over the past 3 years. Considering the association between caries prevalence at age 5 and caries experience at 12 years of age, there is a need for reassessment of the caries preventive programmes for children in Norway.
OBJECTIVE: To report on stability and change in career choices of doctors, between 1 and 3 years after qualification. DESIGN: Postal questionnaire surveys. SETTING: United Kingdom. SUBJECTS: All doctors who qualified in the United Kingdom in 1993. MAIN OUTCOME MEASURES: Choices of eventual career expressed 1 and 3 years after qualifying. RESULTS: The overall pattern of career choices at year 3 differed a little from that at year 1. For example, choices for general practice increased from 26% to 29%, choices for medical specialties fell from 22% to 18%, and for surgical specialties they fell from 17% to 14%. However, because changes of choice between specialties tended to 'cancel out', the aggregated data masked much larger changes when considered at the level of individual doctors. Overall, 74% of respondents retained their year 1 career choice in year 3 (78% of men, 70% of women). Of doctors who chose a hospital specialty in year 1, 71% chose the same specialty in year 3, 18% had switched choice to another hospital specialty, and 9% had switched choice to general practice. The percentage who changed choice from hospital specialties to general practice between years 1 and 3 was lower in the 1993 cohort than in all previous cohorts. Of those whose year 1 choice of long-term career was general practice, 89% retained that choice in year 3 and 11% switched to other branches of medicine. Even by year 3, less than half of all respondents (and a smaller percentage of women than men) signified that their long-term choice of specialty was definite. In year 3, 78% of all respondents, and 79% of doctors from homes in the United Kingdom, intended definitely or probably to practise medicine in the United Kingdom for the foreseeable future, which represented little change from the figures in year 1. CONCLUSIONS: About a quarter of doctors change their career choice between years 1 and 3 after qualification, and less than half regard their choice in year 3 as definite. Flexibility is therefore needed, well beyond the first post-qualification year, to accommodate changes of choice. Where training opportunities in a hospital specialty are limited, doctors are now inclining, more than in the past, to switch to an alternative hospital specialty rather than to general practice.
Accurate, comprehensive follow up of individual medical students is not currently available. The best aggregate data source is probably the Higher Education Funding Council for England (HEFCE). According to their Medical Return tables, 43 131 students began undergraduate medical studies in the United Kingdom (UK) in the decade 1985-94, and 38 376 doctors qualified from UK medical schools in the decade 1990-99, being 89% of the intake numbers 5 years previously. Continuous monitoring is required to enable medical school intake to be adjusted according to the demand for more doctors.
Earlier findings have shown that after unification with the Federal Republic of Germany (FRG) in October 1990 the proportion of very-low-birthweight infants in the former German Democratic Republic (GDR) increased. This study seeks to explore this observation in more detail at the regional level. The analysis of aggregate data of live births in Germany between 1991 and 1997 shows an increasing proportion of very-low-birthweight infants as well as a general trend towards heavier babies in both east and west. The growing proportion of live born infants at very low birthweights in the east, however, seems to be due, in part, to increased registration, most likely reflecting the introduction of the more comprehensive (western) definition of a live birth with unification in October 1990. A fairly distinct east-west pattern in the birthweight distribution present in 1991 had almost disappeared by 1997 and given way to a north-south one.
OBJECTIVES: To determine the willingness to pay (WTP) for the retreatment of insecticide-treated nets (ITN) in four malaria holoendemic communities of Nigeria. METHODS: Contingent valuation method. The study tool was a pretested interviewer-administered questionnaire. Randomly selected households were the study units and household heads or their representatives were interviewed by locally trained interviewers. RESULTS: Most households were willing to pay for annual ITN retreatment in all four communities. The proportion of those willing to pay ranged from 79% to 91%. WTP amounts ranged from $0.05 to $5.26. The median from the aggregated data from the four communities was $0.21. Multivariate analysis showed that many explanatory variables were statistically significantly related to WTP for ITN retreatment. CONCLUSION: WTP for ITN retreatment exists. The difficulty lies in implementing this. One possibility would be a community-based ITN retreatment programme.
In a 5-day retreat at a Salzburg Seminar attended by 64 individuals from 29 countries, teams of health professionals, patient advocates, artists, reporters and social scientists adopted the guiding principle of 'nothing about me without me' and created the country of PeoplePower. Designed to shift health care from 'biomedicine' to 'infomedicine', patients and health workers throughout PeoplePower join in informed, shared decision-making and governance. Drawing, where possible, on computer-based guidance and communication technologies, patients and clinicians contribute actively to the patient record, transcripts of clinical encounters are shared, and patient education occurs primarily in the home, school and community-based organizations. Patients and clinicians jointly develop individual 'quality contracts', serving as building blocks for quality measurement and improvement systems that aggregate data, while reflecting unique attributes of individual patients and clinicians. Patients donate process and outcome data to national data banks that fuel epidemiological research and evidence-based improvement systems. In PeoplePower hospitals, constant patient and employee feedback informs quality improvement work teams of patients and health professionals. Volunteers work actively in all units, patient rooms are information centres that transform their shape and decor as needs and individual preferences dictate, and arts and humanities programmes nourish the spirit. In the community, from the earliest school days the citizenry works with health professionals to adopt responsible health behaviours. Communities join in selecting and educating health professionals and barter systems improve access to care. Finally, lay individuals partner with professionals on all local, regional and national governmental and private health agencies.
The Nosocomial Infection National Surveillance Scheme (NINSS) enables hospitals in England to undertake surveillance of healthcare associated infection, compare their results with national aggregated data, and use the information to improve patient care. A surgical site infection (SSI) module was introduced in 1997, and participation has increased steadily since its inception. This survey was undertaken to assess the views of users on the current service, and how the module should be developed to best meet their needs and resources. Survey forms were sent to infection control teams (ICTs) at the 113 hospitals that had participated at any time during the first three years of the programme. The response rate was 90% (102). The views of users were generally very positive and indicated considerable support for the approach to this type of surveillance. The ability to compare hospital infection rates with national data, the availability of standardized surveillance methods, and centralized data analysis and report production were key reasons for participation for over 80% of users. Most did not wish to see any major changes made to the protocol, although more than a third of users suggested additional data items. Overall, users were satisfied with both the content and timescale for receipt of feedback reports, and 77% disseminated them to at least three groups of clinicians and managers. The majority of ICTs (89%) gave the results directly to the surgeons. For some users (29%) it was too early to assess the value of the surveillance. Of the remainder, although results provided evidence of good performance for some, 46% identified high rates of SSI in one or more groups of surgical patients. In about two-thirds of these hospitals, a review or change in clinical practice was initiated as a result. Three main areas for development were identified: an extended range of surgical procedures, post-discharge surveillance and improved local data collection and analysis systems. Users said they would also like training in handling and interpreting surveillance data. These needs should be addressed in order to ensure the continuing success of national surveillance.
Retrospective aggregate data on all Staphylococcus aureus isolates recovered from blood cultures during 1998 were collected in both jurisdictions on the island of Ireland, Northern Ireland (North) and the Republic of Ireland (South), as part of the North/South Study of MRSA in Ireland 1999. A postal questionnaire was used to gather the data, and all diagnostic microbiology laboratories in the North and 98% of laboratories in the South participated. S. aureus bacteraemia occurred at rates of 20.4 per 100,000 population in the North and 24.5 per 100,000 in the South (missing data from one laboratory). In the North, 22% of patients who had blood cultures positive for S. aureus had methicillin-resistant S. aureus (MRSA) and 25% of S. aureus isolates were MRSA (some patients had more than one isolate). In the South, 31% of patients who had blood cultures positive for S. aureus had MRSA and 36% of S. aureus isolates were MRSA. There was a marked variation in rates between different regions. The percentage of patients with blood cultures positive for S. aureus that had MRSA was considerably lower in the North (22%) than in the South (31%), and in both jurisdictions was lower than that found in England and Wales in 1999 (37%). It is recommended that data on S. aureus bacteraemia and methicillin-resistance rates (already available in many laboratories) are gathered at regional and national level for the surveillance of antimicrobial resistance.
In analogy to the famous saying that war is too serious to leave it to the generals, one could say that the provision of medical care is too serious and too costly to leave it to doctors. This, however.would give the impression of an incongruity which does not exist as an actual factor or as a standpoint in research on the healthcare system. Having said that, there are differences in the methods of observation used: doctors always base their observations on their experiences at the doctor/patient level. In these situations, they are influenced by the therapeutic imperative of wanting to help and their convictions do not allow them to take into account competing requirements or to feel dependent on the higher-level conditions; and the realm of research on the health care system bases its observations more or less on findings derived by means of analysing what is often highly aggregated data, be it of a medical, economic or epidemiological nature. Even though the insights gained at the macrolevel ultimately have to be applied at the microlevel of the doctor/patient relationship, there remains an internal distance from the problems of care which is conducive to proper judgement. From this distant vantage point, researchers attempt to prove the relationship between effort and yield, to indicate weak spots which individual doctors cannot recognise and to define capacity, structure and incentive conditions which guarantee maxi-mum medical care quality. There is, for instance, evidence of astonishing dependence between the medical care provided and incentives for the number of doctor/patient contacts, use of medicines, surgery rates and number of diagnoses. This evidence can be used to draw up recommendations for self-governing bodies in the health care sector and for the political sphere as to how the health care system could be enhanced to achieve a high level of efficiency and quality.
AIMS: Intracytoplasmic sperm injection is a method of assisted reproduction (AR) covered by Statutory Health Care in Germany, since the guidelines of the concerned health authority (Bundesausschuss der Arzte und Krankenkassen--national board of medical doctors and health care insurance) have been changed in 2002, although open questions concerning its risk profile still exist. It is desirable to consider how collection and handling of data about these treatments can be utilised, so that the risks associated with assisted reproduction can be minimised and procedures be regulated in an adequate manner. Therefore this paper investigates the requirements of a national register in order to achieve a fact-based comparison of results. METHOD: Factors influencing the problems around malformation rate and multiple pregnancy in assisted reproduction were searched for in international literature and traced in documentation already available in the German context. Pathways for collection and handling of the problem-associated data are suggested. RESULTS: Up to now relevant data are kept separately. Data links are a precondition, if the existing documentation collected for different purposes should be used to evaluate and survey AR activities. This applies to the following long-standing German data collections: perinatologic and neonatologic survey, obstetric and paediatric patient documentation and the IVF registry. Further more data links to death cause registry and public health data (e. g. health check for school entering children) have to be considered. Comparing different types of international registration best surveys were found by compulsory registries under official control. CONCLUSIONS: Results are suitable for comparison if treatment is carried out under equivalent circumstances and complete standardized data are collected. Foreign examples show that appropriately designed registries contribute to effective assessment in reproductive health technology. Institution-based data aggregation enables benchmarking as means of quality improvement.
We examined the effects of listening to headphone music in ten well trained men (25.1 +/- 6 years) during treadmill running. Maximal oxygen consumption, determined by open circuit spirometry, was followed by two submaximal work bouts 72 hours apart. The work bouts consisted of a supine rest, a 15 minute run at 70% of maximal oxygen consumption, and a three minute active recovery period. Participants listened to music during one of the two trials. Hemodynamic variables and perceived exertion were recorded at three minute intervals during each trial. A venous blood sample, obtained prior to and following each trial, was assayed for norepinephrine and plasma lactate. Analysis of variance revealed significant differences (p < 0.05) between the no music versus the exercise with music trial for (aggregate data 3,6,9,12,15 minutes): heart rate 152.9 +/- 5.3 to 145.9 +/- 4.7 beats x min(-1); systolic blood pressure, 158.1 +/- 3.7 to 151.7 +/- 3.3 mmHg; rate-pressure product 242.2 +/- 11.5 to 222.1 +/- 11.4; exercise lactate 2.75 +/- 0.15 to 2.13 +/- 0.18 mmol x l(-1); and perceived exertion 14.4 +/- 0.4 to 12.9 +/- 0.4. A 17.5% lower level of norepinephrine (841.5 +/- 314.7 to 694.1 +/- 254.5 pg x ml[-1]) in the exercise and music trial was not statistically significant (p<0.05); however a moderate effect size (ES = 0.52) was calculated and may be of practical significance considering the variability of the sample. Higher values for hemodynamics and lactate in the no music trial is suggestive of a greater metabolic demand; however, oxygen consumption was not different. Perhaps the music allowed individuals to relax reducing muscle tension thereby increasing blood flow and lactate clearance while decreasing lactate production in working muscle. The combined results of this study suggest the introduction of music has a psychobiological impact on the exerciser demonstrated by changes in perceived effort, lactate and norepinephrine.
OBJECTIVE: To study caries trends and investigate the possible reasons for changes among 5-year-old Norwegian children in the period 1997-2003. In this cross-sectional analytical time trend study at district, county, and national levels, aggregated data from the Public Dental Services (PDS) and official statistics were used, i.e. number of children and percentage receiving treatment, sale of fluoride tablets, socio-economic background, caries prevalence, and d3mft scores. RESULTS: Caries prevalence increased from 30% in 1997 to just over 40% in 2001, but by 2003 it had dropped to 36%. The corresponding mean number of d3mft were 1.1, 1.6, and 1.4 at national level. Caries prevalence and experience varied considerably between counties and between dental districts throughout the observation period. Multivariate analyses at county level indicated a significant negative association (p < 0.05) between caries prevalence, the sale of fluoride tablets, and net mobility. The impacts of the predictor variables education, income, infant mortality, proportion of immigrants, and the percentage of children treated varied but were rarely significant. CONCLUSIONS: The increasing trend in the prevalence of caries among 5-year-old Norwegian children in the period 1997 to 2001 has reversed. The deterioration in dental health of 5-year-olds after 1997 was associated with a reduction in the sale of fluoride tablets, whereas increased sales of fluoride tablets after 1998 reflect improved caries prevention among preschool children and may explain the improved caries status of these children in 2003.
OBJECTIVES: The purpose of the present investigation was to report on caries experience among Norwegian 12-year-olds from 1985 to 2004 and to assess caries incidence from 12 to 18 years of age for birth cohorts 1973 to 1986. MATERIAL AND METHODS: Aggregated data from the Norwegian Public Dental Services and from official statistics were employed. Information was available about the number of subjects, the proportion receiving treatment, sales of fluoride tablets, socio-demographics, caries prevalence, and the number of decayed, missing, and filled teeth (DMFT). RESULTS: An almost linear decline in caries prevalence and mean D3MFT (dentine level) occurred among 12-year-old children from 1985 until the year 2000, but from 2000 to 2004 an increasing trend was observed. The highest mean 6-year D3MFT increment (age 12-18 years) was 4.1 (cohort 1976), while the lowest was 3.2 (cohorts 1982 and 1983). In multiple linear regression analyses of trend, baseline D3MFT accounted for more than 91% of total explained variance in D3MFT increment (Models I and III). Without baseline D3MFT as predictor (Models II and IV), there was a significant association between education, social assistance, mobility, infant mortality, percentage examined, and the additive interaction terms year + income and year + education and D3MFT increment after controlling for confounding and multicollinearity. CONCLUSIONS: Four consecutive years of increase in caries experience among 12-year-old children after 15 years of decline and evidence of stability or increase of the caries increment from 12 to 18 years of age among Norwegian teenagers give cause for concern.
Sprague-Dawley (SD) rats were given X-irradiation (150 R) on Day 17 of gestation. After birth, all male pups were pooled once and then assigned randomly to irradiated mothers and control mothers. Offspring were administered an open-field test at about 7 weeks of age. The analysis was performed on the basis of two approaches: In the per subject approach, individual subject data (aggregation across Day 2 through Day 4) were treated as the basic unit of statistical analysis. In the per litter approach, double aggregation (aggregation across Day 2 through Day 4 for each subject and aggregation across subjects within each litter) was used. The per subject approach was slightly more sensitive as to the treatment effect, but it induced a reduction in the magnitude of eta squared. A principal component analysis was performed using eta squared together with those of several reference groups. Results were plotted on a map constructed from component scores. The characteristics of behavior in X-irradiated rats were very similar to those of the earlier stage of trials in terms of the location on the map. The postnatal maternal effect on open-field behavior was not serious and was adequately negligible in practice. A new fostering procedure was proposed and its advantages discussed.
Research has shown that people misremember right-looking heads on coins as facing to the left, suggesting a general memory schema that favors left-lookers. This hypothesis was investigated in a study of 241 subjects in three experiments who were shown photographs of faces looking to the left, to the right, or at the observer and were later asked to identify whether each one had subsequently been left-right reversed. Also, in Experiments 2 and 3, respectively, initial judgments of liking and of orientation were obtained. Unexpectedly, orientation memory accuracy was lower after a 5-s exposure than after a 1-s exposure, and after initial judgments of lateral orientation than after judgments of liking. Although the difference between left- and right-lookers was significant in only 2 of 14 comparisons, aggregated data showed that identification accuracy was generally higher for left-lookers, with a mean effect size of 0.16. Although small, this difference is consistent with the hypothesis of a left-looking schema for heads.
Using data from 59 countries, we conducted an international comparison study to identify nutritional predictors of age-adjusted oral and esophageal cancer mortality rates. Statistical models accounted for per capita tobacco disappearance data, alcohol consumption, and various measures of socioeconomic status. For oral cancer, stepwise regression results showed protective effects for milk/dairy products (B = -0.030, p < 0.0001) and cabbage consumption (B = -0.391, p = 0.01) and increased risk from vegetable oil (B = 0.072, p = 0.04) and excess animal fat calories (B = 0.344, p < 0.0001) as well as marginally increased risk from cereals (B = 0.008, p = 0.08). Results were obtained after accounting for all background factors, including sex (model R2 = 0.52). For esophageal cancer, stepwise results indicated protective effects for fruit (B = -0.046, p = 0.0006) and total caloric intake (B = -0.013, p < 0.0001) and increased risk from vegetable oil (B = 0.061, p = 0.04) and meat (B = 0.031, p < 0.0001) consumption (model R2 = 0.55). When analyzed separately by sex, results were similar, indicating that the risk factors are probably the same in both sexes, even though women consistently have fewer deaths, on average, from these cancers. On the basis of results from stepwise regression models, we also fitted general linear models for mortality rates of each cancer site, and results were similar in terms of magnitude and direction of effects. Although the evidence provided by this type of analysis using data aggregated by country is limited in terms of control for potential confounding effects and modeling of possible effect modification, an effect of high meat, animal product, or vegetable oil and low fruit and cabbage consumption is consistent with the known biology of these tumors.