The impact of National Death Index linkages on population-based cancer survival rates in the United States

Background: In order to ensure accurate survival estimates, population-based cancer registries must ascertain all, or nearly all, patients diagnosed with cancer in their catchment area, and obtain complete follow-up information on all deaths that occurred among registered cancer patients. In the US, linkage with state death records may not be sufficient to ascertain all deaths. Since 1979, all state vital statistics offices have reported their death certificate information to the National Death Index (NDI). Objective: This study was designed to measure the impact of linkage with the NDI on population-based relative and cancer cause-specific survival rates in the US. Methods: Central cancer registry records for patients diagnosed 1993–1995 from California, Colorado, and Idaho were linked with death certificate information (deaths 1993–2004) from their individual state vital statistics offices and with the NDI. Two databases were created: one contained incident records with deceased patients linked only to state death records and the second database contained incident records with deceased patients linked to both state death records and the NDI. Survival estimates and 95% confidence intervals from each database were compared by state and primary site category. Results: At 60 months follow-up, 42.1–48.1% of incident records linked with state death records and an additional 0.7–3.4% of records linked with the NDI. Survival point estimates from the analysis without NDI were not contained within the corresponding 95% CIs from the NDI augmented analysis for all sites combined and colorectal, pancreas, lung and bronchus, breast, prostate, non-Hodgkin lymphoma, and Kaposi sarcoma cases in all 3 states using relative survival methods. Additional combinations of state and primary site had significant survival estimate differences, which differed by method (relative versus cause-specific survival). Conclusion: To ensure accurate population-based cancer survival rates, linkage with the National Death Index to ascertain out of state and late registered deaths is a necessary process for US central cancer registries.     

The validity of cancer information on death certificates in Norway and the impact of death certificate initiated cases on cancer incidence and survival

BackgroundDeath certificates are an important source of information for cancer registries. The aim of this study was to validate the cancer information on death certificates, and to investigate the effect of including death certificate initiated (DCI) cases in the Cancer Registry of Norway when estimating cancer incidence and survival.MethodsAll deaths in Norway in the period 2011–2015 with cancer mentioned on the death certificates were linked to the cancer registry. Notifications not registered from other sources were labelled death certificate notifications (DCNs), and considered as either cancer or not, based on available information in the registry or from trace-back to another source.ResultsFrom the total of 65 091 cancers mentioned on death certificates in the period 2011–2015, 58,425 (89.8%) were already in the registry. Of the remaining 6 666 notifications, 2 636 (2 129 with cancer as underlying cause) were not regarded to be new cancers, which constitutes 4.0% of all cancers mentioned on death certificates and 39.5% of the DCNs. Inclusion of the DCI cases increased the incidence of all cancers combined by 2.6%, with largest differences for cancers with poorer prognosis and for older age groups. Without validation, including the 2 129 disregarded death certificates would over-estimate the incidence by 1.3%. Including DCI cases decreased the five-year relative survival estimate for all cancer sites combined with 0.5% points.ConclusionIn this study, almost 40% of the DCNs were regarded not to be a new cancer case, indicating unreliability of death certificate information for cancers that are not already registered from other sources. The majority of the DCNs where, however, registered as new cases that would have been missed without death certificates. Both including and excluding the DCI cases will potentially bias the survival estimates, but in different directions. This biases were shown to be small in the Cancer Registry of Norway.     

Using birth defects registry data to evaluate infant and childhood mortality associated with birth defects: an alternative to traditional mortality assessment using underlying cause of death statistics

BACKGROUND: Although birth defects are a leading cause of death in infancy and early childhood, the proportion of all deaths to children with clinically diagnosed birth defects is not well documented. The study is intended to measure the proportion of all deaths to infants and children under age 10 occurring to children with birth defects and how and why this proportion differs from the proportion of deaths due to an underlying cause of congenital anomalies using standard mortality statistics. METHODS: A linked file of Michigan livebirths and deaths was combined with data from a comprehensive multisource birth defects registry of Michigan livebirths born during the years 1992 through 2000. The data were analyzed to determine the mortality rate for infants and children with birth defects and for children with no reported birth defect. Mortality risk ratios were calculated. The underlying causes of death for children with birth defects were also categorized and compared to cause- specific mortality rates for the general population. RESULTS: Congenital anomalies were the underlying cause of death for 17.8% of all infant deaths while infants with birth defects were 33.7% of all infant deaths in the study. Almost half of all Michigan deaths to children aged 1 to 2 were within the birth defects registry, though only 15.0% had an underlying cause of death of a congenital anomaly based upon standard mortality statistics. The mortality experience among children with birth defects was significantly higher than other children throughout the first 9 years of life, ranging from 4.6 for 5 year olds to 12.8 for children 1 to 2. Mortality risk ratios examined by cause of death for infants with birth defects were highest for other endocrine (28.1), other CNS (28.1), and heart (21.9) conditions. For children 1 through 9, the highest differential risk was seen for other perinatal conditions (39.0), other endocrine (29.7), other CNS (24.5), and heart (21.4). CONCLUSIONS: Childhood mortality analyses that incorporate birth defects registry data provide a more comprehensive picture of the full burden of birth defects on mortality in infant and children and can provide an effective mechanism for monitoring the survival and mortality risks of children with selected birth defects on a population basis.     

Cancer mortality in Itapúa—A rural province of Paraguay 2003–2012

BackgroundItapúa is a rural department in Paraguay with a population of about 500,000 and a high degree of agro-mechanization for the production of soybean and other crops. So far, only basic health care is provided. Here we analyzed the cancer mortality in this region as a first step towards epidemiological data for cancer prevention.MethodsWe calculated the age-adjusted mortality rates according to world standard (AMRWs) for the major cancer sites in both males and females between 2003 and 2012, and estimated the differences between the capital and more central districts of Itapúa vs. remote districts.ResultsThere were about 2000 cancer deaths in the decade studied, with AMRWs for all malignancies of 90.9/100,000 in males from central vs. 49.1/100,000 in remote districts and 69.0/100,000 vs. 45.0/100,000 in women. Cancer was mentioned in 12.4% of all death certificates and outweighed mortality from certain infectious and parasitic diseases (3.6%). Cause of death was ill-defined in 19.6% of all death certificates, especially in remote regions and among the elderly. The part of cancer located in the uterus (47.8%) or cell type of neoplasm of the lymphatic or hematopoietic system (73.1%) were often not specified. The uterus (mainly the cervix) (C53–C55) was the leading cancer site in women with AMRWs of 17.2/100,000 in central and 14.0/100,000 in remote districts, followed by the breast. Lung and prostate were the leading cancer sites among men. The lung cancer mortality rate was 19.3/100,000 in the central region but 9.5/100,000 in remote districts. Although children comprised 36% of the population, only 24 death certificates listed cancer as cause of death in this decade.ConclusionsAnalysis of cancer mortality in this rural region of Paraguay, which lacks resources for diagnostics and care, revealed an already large number of cases, with higher rates in the central region than in remote districts. Lung and uterus (primarily the cervix) are common cancer sites and indicate the potential for prevention. However, the quality of the vital statistics needs to be improved. The true cancer burden is most likely underestimated, especially in remote regions and children.     

Recent decline in the U.S. death rate from myeloproliferative neoplasms, 1999-2006

Background: Myeloproliferative neoplasms (MPNs) are classified as neoplasms of uncertain or unknown behavior in the International Classification of Diseases (ICD) Version 10 and can contribute to risk of death from complications (especially thrombosis). Methods: U.S age-standardized death rates using ICD-Version 10 codes relevant to classical MPN (i.e., polycythemia vera, essential thrombocythemia, and “chronic myeloproliferative disease”) were examined for 1999–2006. The underlying cause of death and also all causes (“multiple causes” or “mentions”) coded on death certificates were considered. Trends were assessed by using percentage change (PC) in rate between 1999 and 2006, and annual percentage change (APC) estimated from linear regression. Results: The decline in death rates was large for MPN, whether based only the underlying cause (PC = ?19.7%, APC = ?3.4%) or on the substantially higher rates based on any cause (PC = ?24.1%, APC = ?3.8%), and was consistent by gender and age group (<65 and 65+ years). For deaths with MPN coded as other than the underlying cause, cardiovascular diseases were the most common underlying cause and the ASR for these deaths declined substantially (PC = ?40.0%). Conclusions: Use of the underlying cause of death in surveillance will considerably underestimate MPN-related mortality rates in the population. Studies are needed on treatment in random samples of MPN patients from population-based cancer registries. Continued surveillance of MPN-related mortality rates in the population is needed in view of recent attempts (including the use of aspirin) to control cardiovascular complications of MPN.     

Causes of death in men with prostate cancer: Results from the Danish Prostate Cancer Registry (DAPROCAdata)

BackgroundCurrent knowledge of the validity of registry data on prostate cancer-specific death is limited. We aimed to determine the underlying cause of death among Danish men with prostate cancer, to estimate the level of misattribution of prostate cancer death, and to examine the risk of death from prostate cancer when accounting for competing risk of death.Material and methodsWe investigated a nationwide cohort of 15,878 prostate cancer patients diagnosed in 2010–2014; with 3343 deaths occurring through 2016. Blinded medical chart review was carried out for 670 deaths and compared to the national cause of death registry. Five death categories were defined: 1) prostate cancer-specific death, 2) other unspecified urological cancer death, 3) other cancer death 4) cardiovascular disease death, and 5) other causes of death. Competing risk analyses compared Cox cause-specific and Fine-Gray regression models.ResultsChart review attributed 51.2% of deaths to prostate cancer, 17.0% to cardiovascular disease, and 16.7% to other causes. The Danish Register of Causes of Death attributed 71.7% of deaths to prostate cancer when including all registered contributing causes of death, and 57.0% of deaths when including only the primary registered cause of death. The probability of death by prostate cancer was 10% at 2-year survival.ConclusionsMore than half of the deceased men in our study cohort died of their prostate cancer disease within a mean of 2.4 years of follow up. Data from the death registry is prone to misclassification, potentially overestimating the proportion of deaths from prostate cancer.     

Improving the accuracy of death certification

BACKGROUND: Population-based mortality statistics are derived from the information recorded on death certificates. This information is used for many important purposes, such as the development of public health programs and the allocation of health care resources. Although most physicians are confronted with the task of completing death certificates, many do not receive adequate training in this skill. Resulting inaccuracies in information undermine the quality of the data derived from death certificates. METHODS: An educational intervention was designed and implemented to improve internal medicine residents'' accuracy in death certificate completion. A total of 229 death certificates (146 completed before and 83 completed after the intervention) were audited for major and minor errors, and the rates of errors before and after the intervention were compared. RESULTS: Major errors were identified on 32.9% of the death certificates completed before the intervention, a rate comparable to previously reported rates for internal medicine services in teaching hospitals. Following the intervention the major error rate decreased to 15.7% (p = 0.01). The reduction in the major error rate was accounted for by significant reductions in the rate of listing of mechanism of death without a legitimate underlying cause of death (15.8% v. 4.8%) (p = 0.01) and the rate of improper sequencing of death certificate information (15.8% v. 6.0%) (p = 0.03). INTERPRETATION: Errors are common in the completion of death certificates in the inpatient teaching hospital setting. The accuracy of death certification can be improved with the implementation of a simple educational intervention.     

Temporal trends in net and crude probability of death from cancer and other causes in the Australian population, 1984–2013

BackgroundWhile net probabilities of death in the relative survival framework ignore competing causes of death, crude probabilities allow estimation of the real risk of cancer deaths. This study quantifies temporal trends in net and crude probabilities of death.MethodsAustralian population-based cohort of 2,015,903 people aged 15-89 years, diagnosed with a single primary invasive cancer from 1984 to 2013 with mortality follow-up to 31 December 2014. Survival was analyzed with the cohort method. Flexible parametric relative survival models were used to estimate both probability measures by diagnosis year for all cancers and selected leading sites.ResultsFor each site, excess mortality rates reduced over time, especially for prostate cancer. While both the 10-year net and crude probability of cancer deaths decreased over time, specific patterns varied. For example, the crude probability of lung cancer deaths for males aged 50 years decreased from 0.90 (1984) to 0.79 (2013); whereas the corresponding probabilities for kidney cancer were 0.64 and 0.18 respectively. Patterns for crude probabilities of competing deaths were relatively constant. Although for younger patients, both net and crude measures were similar, crude probability of competing deaths increased with age, hence for older ages net and crude measures were different except for lung and pancreas cancers.ConclusionsThe observed reductions in probabilities of death over three decades for Australian cancer patients are encouraging. However, this study also highlights the ongoing mortality burden following a cancer diagnosis, and the need for continuing efforts to improve cancer prevention, diagnosis and treatment.     

Improving the reporting of cancer-specific mortality and survival in research using cancer registry data

Population-based registries are increasingly used in cancer research. In such studies, cancer-specific mortality or survival is frequently used as the primary outcome. To determine whether a putative cancer was part of the causal chain of events leading to death, cancer registries primarily rely on death certificates. Hence, they depend on the subjective interpretation of information available to medical examiners at the time of death. Misclassification may occur: studies report misclassification of cancer as a cause of death in 15%–35% of death certificates based on evaluation by expert panels and/or autopsy reports. Further misclassification may occur when coding death causes in the cancer registry. Researchers should be aware of potential misclassification bias when using cancer registry data. Differential misclassification may bias the results towards or away from the null hypothesis, depending on whether there is relative over- or under-reporting of cancer-related deaths in one group. Strategies to improve reporting of cancer-specific survival/mortality include (1) describing the procedure used to identify cancer-specific deaths; (2) considering the use of multiple definitions of cancer-related deaths (strict/liberal definitions of cancer-specific deaths, and/or addition of relative survival as an outcome); and (3) reporting cancer-specific survival/mortality together with the objectively measured parameters overall survival or all-cause mortality.     

Adjusting for the proportion of cancer deaths in the general population when using relative survival: a sensitivity analysis

Background: Relative survival is an extensively used method in population based cancer studies as it provides a measure of survival without the need for accurate cause of death information. It gives an estimate for the probability of dying from cancer in the absence of other causes by estimating the excess mortality in the study population when compared to an external group. The external group is usually the general population within a country or state and mortality estimates are taken from national life tables that are broken down by age, sex, calendar year and, where applicable, race/ethnicity. One potential bias when using relative survival that is most often overlooked occurs when there are a high proportion of deaths due to a specific cancer in the external group. Methods: This paper uses data from the Finnish Cancer Registry to illustrate, through the use of a simple sensitivity analysis, the impact that specific cancer deaths in the population mortality figures can have on the estimate of relative survival. Results: We found that when examining specific diseases such as breast cancer and colon cancer, the proportion of deaths due to these specific cancers in the general population is so small in comparison to the total mortality that they make little difference to the relative survival estimates. However, prostate cancer proved to be an exception to this. For all cancer sites combined the sensitivity analysis illustrates a major limitation for this type of analysis, particularly with the older age groups. Conclusion: We recommend that, with a classification of diseases as wide as all cancer sites, relative survival should not be used without appropriate adjustment.     

Cancer of the Breast in Ontario

The breast is the leading cancer site among women; it accounts for 20% of all female cancer deaths. The lifetime probability of death from breast cancer for a female born in Ontario is 3.3%; that is, one in every 30 women will die of breast cancer. The risk of developing breast cancer is almost twice this figure.The medical certificate of death yields a reliable estimate of the number of persons who die of breast cancer, and the level of the age-specific breast cancer death rates has not changed over the past 30 years. Cohort analysis yields an indistinguishable mortality pattern for succeeding cohorts of women from 1871. Available information indicates no change in incidence.The stable mortality and incidence rates suggest that there has been little or no change in the survival rate, despite emphasis on early diagnosis and improvement in therapeutic skills and in technical facilities.     

Human echinococcosis mortality in the United States, 1990-2007

Background

Despite the endemic nature of Echinococcus granulosus and Echinococcus multilocularis infection in regions of the United States (US), there is a lack of data on echinococcosis-related mortality. To measure echinococcosis-associated mortality in the US and assess possible racial/ethnic disparities, we reviewed national-death certificate data for an 18-year period.

Methodology/Principal Findings

Echinococcosis-associated deaths from 1990 through 2007 were identified from multiple-cause-coded death records and were combined with US census data to calculate mortality rates. A total of 41 echinococcosis-associated deaths occurred over the 18-year study period. Mortality rates were highest in males, Native Americans, Asians/Pacific Islanders, Hispanics and persons 75 years of age and older. Almost a quarter of fatal echinococcosis-related cases occurred in residents of California. Foreign-born persons accounted for the majority of echinococcosis-related deaths; however, both of the fatalities in Native Americans and almost half of the deaths in whites were among US-born individuals.

Conclusions/Significance

Although uncommon, echinococcosis-related deaths occur in the US. Clinicians should be aware of the diagnosis, particularly in foreign-born patients from Echinococcus endemic areas, and should consider tropical infectious disease consultation early.     

Lack of significant associations between single nucleotide polymorphisms in LPAL2-LPA genetic region and all cancer incidence and mortality in Japanese population: The Japan public health center-based prospective study

BackgroundHigh lipoprotein (a) level is an established cardiovascular risk, but its association with non-cardiovascular diseases, especially cancer, is controversial. Serum lipoprotein (a) levels vary widely by genetic backgrounds and are largely determined by the genetic variations of apolipoprotein (a) gene, LPA. In this study, we investigate the association between SNPs in LPA region and cancer incidence and mortality in Japanese.MethodsA genetic cohort study was conducted utilizing the data from 9923 participants in the Japan Public Health Center-based Prospective Study (JPHC Study). Twenty-five SNPs in the LPAL2-LPA region were selected from the genome-wide genotyped data. Cox regression analysis adjusted for the covariates and competing risks of death from other causes, were used to estimate the relative risk (hazard ratios (HR) with 95% confidence intervals (CI)) of overall and site-specific cancer incidence and mortality, for each SNP.ResultsNo significant association was found between SNPs in the LPAL2-LPA region and cancer incidence or mortality (overall/site-specific cancer). In men, however, HRs for stomach cancer incidence of 18SNPs were estimated higher than 1.5 (e.g., 2.15 for rs13202636, model free, 95%CI: 1.28–3.62) and those for stomach cancer mortality of 2SNPs (rs9365171, rs1367211) were estimated 2.13 (recessive, 95%CI:1.04–4.37) and 1.61 (additive, 95%CI: 1.00–2.59). Additionally, the minor allele for SNP rs3798220 showed increased death risk from colorectal cancer (CRC) in men (HR: 3.29, 95% CI:1.59 – 6.81) and decreased CRC incidence risk in women (HR: 0.46, 95%CI: 0.22–0.94). Minor allele carrier of any of 4SNPs could have risk of prostate cancer incidence (e.g., rs9365171 dominant, HR: 1.71, 95%CI: 1.06–2.77).ConclusionsNone of the 25 SNPs in the LPAL2-LPA region was found to be significantly associated with cancer incidence or mortality. Considering the possible association between SNPs in LPAL2-LPA region and colorectal, prostate and stomach cancer incidence or mortality, further analysis using different cohorts is warranted.     

Cancer mortality in a population-based cohort of American Indians – The strong heart study

BackgroundCancer mortality among American Indian (AI) people varies widely, but factors associated with cancer mortality are infrequently assessed.MethodsCancer deaths were identified from death certificate data for 3516 participants of the Strong Heart Study, a population-based cohort study of AI adults ages 45–74 years in Arizona, Oklahoma, and North and South Dakota. Cancer mortality was calculated by age, sex and region. Cox proportional hazards model was used to assess independent associations between baseline factors in 1989 and cancer death by 2010.ResultsAfter a median follow-up of 15.3 years, the cancer death rate per 1000 person-years was 6.33 (95 % CI 5.67–7.04). Cancer mortality was highest among men in North/South Dakota (8.18; 95 % CI 6.46–10.23) and lowest among women in Arizona (4.57; 95 % CI 2.87–6.92). Factors independently associated with increased cancer mortality included age, current or former smoking, waist circumference, albuminuria, urinary cadmium, and prior cancer history. Factors associated with decreased cancer mortality included Oklahoma compared to Dakota residence, higher body mass index and total cholesterol. Sex was not associated with cancer mortality. Lung cancer was the leading cause of cancer mortality overall (1.56/1000 person-years), but no lung cancer deaths occurred among Arizona participants. Mortality from unspecified cancer was relatively high (0.48/100 person-years; 95 % CI 0.32−0.71).ConclusionsRegional variation in AI cancer mortality persisted despite adjustment for individual risk factors. Mortality from unspecified cancer was high. Better understanding of regional differences in cancer mortality, and better classification of cancer deaths, will help healthcare programs address cancer in AI communities.     

Trends in schistosomiasis-related mortality in Brazil, 2000–2011

Schistosomiasis is an important public health problem, with high morbidity and mortality in endemic countries. We analysed the epidemiological characteristics and time trends of schistosomiasis-related mortality in Brazil. We performed a nationwide study based on official mortality data obtained from the Brazilian Mortality Information System. We included all deaths in Brazil between 2000 and 2011, in which schistosomiasis was mentioned on the death certificate as an underlying or associated cause of death (multiple causes of death). We calculated crude and age-adjusted mortality rates (per 100,000 inhabitants), and proportional mortality rates. Trends over time were assessed using joinpoint regression models. Over the 12-year study period, 12,491,280 deaths were recorded in Brazil. Schistosomiasis was mentioned in 8,756 deaths, including in 6,319 (72.2%) as an underlying cause and in 2,437 (27.8%) as an associated cause. The average annual age-adjusted mortality rate was 0.49 deaths/100,000 inhabitants (95% confidence interval: 0.46–0.52) and proportional mortality rate was 0.070% (95% confidence interval: 0.069–0.072). Males (0.53 deaths/100,000 inhabitants), those aged ⩾70 years (3.41 deaths/100,000 inhabitants), those of brown race/colour (0.44 deaths/100,000 inhabitants), and residents in the Northeast region of Brazil (1.19 deaths/100,000 inhabitants) had the highest schistosomiasis-related death rates. Age-adjusted mortality rates showed a significant decrease at a national level (Annual Percent Change: −2.8%; 95% confidence interval: −4.2 to −2.4) during the studied period. We observed decreasing mortality rates in the Northeast (Annual Percent Change: −2.5%; 95% confidence interval: −4.2 to −0.8), Southeast (Annual Percent Change: −2.2%; 95% confidence interval: −3.6 to −0.9), and Central-West (Annual Percent Change: −7.9%; 95% confidence interval: −11.3 to −4.3) regions, while the rates remained stable in the North and South regions. Despite the reduced mortality, schistosomiasis is still a neglected cause of death in Brazil, with considerable regional differences. Sustainable control measures should focus on increased coverage, and intensified and tailored control measures, to prevent the occurrence of severe forms of schistosomiasis and associated deaths.     

Mortality of workers at the Sellafield plant of British Nuclear Fuels.

The mortality of all 14,327 people who were known to have been employed at the Sellafield plant of British Nuclear Fuels at any time between the opening of the site in 1947 and 31 December 1975 was studied up to the end of 1983. The vital state of 96% of the workers was traced satisfactorily and 2277 were found to have died, 572 (25%) from cancer. On average the workers suffered a mortality from all causes that was 2% less than that of the general population of England and Wales and 9% less than that of the population of Cumberland (the area in which the plant is sited). Their mortality from cancers of all kinds was 5% less than that of England and Wales and 3% less than that of Cumberland. In the five years after their first employment Sellafield workers had an overall mortality that was 70% of that of England and Wales, probably due to healthier members of the population being selected for employment. Raised death rates from cancers of several specific sites were found, but only for those of ill defined and secondary sites was the excess statistically significant (30 observed, 19.7 expected). For cancers of the liver and gall bladder there was a significant deficit of deaths (four observed, 10.5 expected). Workers in areas of the plant where radiation exposure was likely were issued with dosimeters to measure their external exposure to ionising radiations. Personal dose records were maintained for workers who entered such areas other than infrequently. Workers with personal dose records ("radiation" workers) had lower death rates from all causes combined than other workers but the death rates from cancer in the two groups were similar. Compared with the general population radiation workers had statistically significant deficits of liver and gall bladder cancer, lung cancer, and Hodgkin''s disease. There were excesses of deaths from myeloma (seven observed, 4.2 expected) and prostatic cancer (19 observed, 15.8 expected) but these were not significant and there was no evidence of an excess of leukaemia (10 deaths observed, 12.2 expected) or cancer of the pancreas (15 observed, 17.8 expected). Non-radiation workers had a significant deficit of leukaemia (one death observed, 5.1 expected) and a significant excess of cancers of ill defined and secondary sites (13 deaths observed, 5.8 expected). For no type of cancer was the ratio of observed to expected deaths significantly different between radiation and non-radiation workers.(ABSTRACT TRUNCATED AT 400 WORDS)     

Explaining differences in English hospital death rates using routinely collected data

ObjectivesTo ascertain hospital inpatient mortality in England and to determine which factors best explain variation in standardised hospital death ratios.DesignWeighted linear regression analysis of routinely collected data over four years, with hospital standardised mortality ratios as the dependent variable.SettingEngland.SubjectsEight million discharges from NHS hospitals when the primary diagnosis was one of the diagnoses accounting for 80% of inpatient deaths.ResultsThe four year crude death rates varied across hospitals from 3.4% to 13.6% (average for England 8.5%), and standardised hospital mortality ratios ranged from 53 to 137 (average for England 100). The percentage of cases that were emergency admissions (60% of total hospital admissions) was the best predictor of this variation in mortality, with the ratio of hospital doctors to beds and general practitioners to head of population the next best predictors. When analyses were restricted to emergency admissions (which covered 93% of all patient deaths analysed) number of doctors per bed was the best predictor.ConclusionAnalysis of hospital episode statistics reveals wide variation in standardised hospital mortality ratios in England. The percentage of total admissions classified as emergencies is the most powerful predictor of variation in mortality. The ratios of doctors to head of population served, both in hospital and in general practice, seem to be critical determinants of standardised hospital death rates; the higher these ratios, the lower the death rates in both cases.

Key messages

• Between 1991-2 and 1994-5 average standardised hospital mortality ratios in English hospitals reduced by 2.6% annually, but the ratios varied more than twofold among the hospitals
• After adjustment for the percentage of emergency cases and for age, sex, and primary diagnosis, the best predictors of standardised hospital death rates were the numbers of hospital doctors per bed and of general practitioners per head of population in the localities from which hospital admissions were drawn
• England has one of the lowest number of physicians per head of population of the OECD countries, being only 59% of the OECD average
• It is now possible to control for factors outside the direct influence of hospital policy and thereby produce a more valid measure of hospital quality of care

     

Estimating bias in causes of death ascertainment in the Finnish Randomized Study of Screening for Prostate Cancer

BackgroundPrecise cause of death (CoD) ascertainment is crucial in any cancer screening trial to avoid bias from misclassification due to excessive recording of diagnosed cancer as a CoD in death certificates instead of non-cancer disease that actually caused death. We estimated whether there was bias in CoD determination between screening (SA) and control arms (CA) in a population-based prostate cancer (PCa) screening trial.MethodsOur trial is the largest component of the European Randomized Study of Screening for Prostate Cancer with more than 80,000 men. Randomly selected deaths in men with PCa (N = 442/2568 cases, 17.2%) were reviewed by an independent CoD committee. Median follow-up was 16.8 years in both arms.ResultsOverdiagnosis of PCa was present in the SA as the risk ratio for PCa incidence was 1.19 (95% confidence interval (CI) 1.14–1.24). The hazard ratio (HR) for PCa mortality was 0.94 (95%CI 0.82–1.08) in favor of the SA. Agreement with official CoD registry was 94.6% (κ = 0.88) in the SA and 95.4% (κ = 0.91) in the CA. Altogether 14 PCa deaths were estimated as false-positive in both arms and exclusion of these resulted in HR 0.92 (95% CI 0.80–1.06).ConclusionsA small differential misclassification bias in ascertainment of CoD was present, most likely due to attribution bias (overdiagnosis in the SA). Maximum precision in CoD ascertainment can only be achieved with independent review of all deaths in the diseased population. However, this is cumbersome and expensive and may provide little benefit compared to random sampling.     

Deaths from rhesus haemolytic disease in England and Wales in 1977: accuracy of records and assessment of anti-D prophylaxis.

All the death certificates for deaths in 1977 where haemolytic disease of the newborn (HDN) was the principal, an antecedent, or a contributory cause were obtained from the Office of Population Censuses and Surveys (OPCS). The hospital notes of all 54 of the live-born cases and all of the 101 stillbirths were also obtained. The cause of the death indicated by the notes was compared with the cause and coding on the death certificate. In about a quarter of the cases death was not due to haemolytic disease of any type. The commonest errors arose because the International Classification of Diseases (8th edition) stipulates that hydrops without mention of cause should be coded as HDN and because stillbirths to rhesus-negative mothers tend to be attributed to rhesus HDN automatically. Though deaths from HDN may be overestimated in this way, they are also underestimated because rhesus disease, although mentioned on the certificate, is not selected as the underlying cause, which it may be. These cases were found through multiple coding of all the contributory causes of death, which OPCS performs on a 25% sample of all death certificates for research purposes. These two sources of inaccuracy tend to cancel each other out, but statistics from death certificates give a misleading picture of the efficacy of anti-D prophylaxis because anti-D can never prevent cases which are not in fact due to rhesus HDN. Most of the mothers studied had become immunised before anti-D became available, but in those who could have been treated 75% had not received prophylaxis. As this was a sample of deaths, however, it would not be accurate to extrapolate this high figure to the population at risk. Nevertheless, the organisation of prophylaxis is clearly deficient and should be remedied before providing antenatal anti-D to supplement postnatal treatment.