Drug-related deaths: Statistics based on death certificates miss one-third of cases.

Aims: Statistics on drug-related deaths (DRD) provide crucial information on the drug situation. The European Monitoring Centre for Drug and Drug Addiction (EMCDDA) has published a specification for extracting DRD from national mortality registers to be used in international comparisons. However, surprisingly little is known of the accuracy of DRD statistics derived from national mortality registers. This study assesses the accuracy of Swedish data derived from national mortality registers by comparing it with other sources of data. Methods: We compared five Swedish datasets. Three were derived from national mortality registers, two according to a Swedish specification and one according to the EMCDDA specification. A fourth dataset was based on toxicological analyses. We used a fifth dataset, an inventory of DRD in Stockholm, to assess the completeness and coverage of the Swedish datasets. Results: All datasets were extracted from high-quality registers, but still did not capture all DRD, and both the numbers and demographic characteristics varied considerably. However, the time trends were consistent between the selections. In international comparisons, data completeness and investigation procedures may impact even more on stated numbers. Conclusions: Basing international comparisons on numbers or rates of DRDs gives misleading results, but comparing trends is still meaningful.

Opioid-related deaths and previous care for drug use and pain relief in Sweden.

AIM: In 2006-2014, the rate of drug-related deaths, typically opioid poisonings, more than doubled in Sweden. Opioid prescriptions for pain control or opioid agonist therapy also increased. In this retrospective study, we compared death rates between individuals whose first recorded contact with prescribed opioids was for pain control and individuals that had received substance use disorder (SUD) treatment before their first recorded opioid prescription. METHODS: We included 2834 forensically examined individuals (ages 15-64 years) that died of poisoning in Sweden in 2006-2014. For each death we acquired data on previous opioid prescriptions and SUD treatments. We compared three study groups: pain control (n = 788); a SUD treatment group (n = 1629); and a group with no prescription for pain control or SUD treatment (n = 417). RESULTS: Overall fatal poisonings increased from 2.77 to 7.79 (per 100,000 individuals) from 2006 to 2014 (relative 181% increase). Fatal poisoning increased from 2006 to 2014 by 269% in the pain control group (0.64 to 2.36 per 100,000) and by 238% in the SUD treatment group (1.35 to 4.57 per 100,000). Heroin-related deaths remained constant; consequently, the increase was likely attributable to prescription opioids. CONCLUSION: A rapid increase in deaths attributable mainly to prescription opioids for pain control, was reported previously in the United States. Our study indicated that increased access to prescription opioids might contribute to higher death rates also in Sweden among patients seeking pain control and individuals with an established SUD; however, deaths related to prescription opioids mainly occurred among those with SUDs.

Accuracy of mortality statistics in Palestine: a retrospective cohort study.

OBJECTIVE: To examine the accuracy of mortality statistics in Palestine, to identify gaps and to provide evidence-based recommendations to improve mortality statistics in Palestine. STUDY DESIGN AND SETTING: A retrospective death registry-based study that examined a stratified random sample of death notification forms (DNFs) of patients who died in hospitals in Palestine was reported in 2012. We randomly selected 600 deceased from the Cause of Death Registry: 400 from the West Bank and 200 from the Gaza Strip. Analysis was based on the randomly selected deaths that we were able to retrieve the medical records for; 371 deaths in the West Bank and 199 deaths in the Gaza Strip. RESULTS: Data in the Palestinian Health Information Centre (PHIC) registry had a low degree of accuracy: less than half of the underlying causes stated the correct cause of death. In general, deaths due to malignant neoplasms were more accurately reported on DNFs than other causes of death, and metabolic diseases (including diabetes) were the most problematic. Issues with coding and classification at the PHIC were most apparent for perinatal conditions and congenital anomalies. CONCLUSION: Procedures for coding and classification at the PHIC deviate considerably from the international norms defined in the International Statistical Classification of Diseases and Related Health Problems (ICD) and account to a considerable extent for the discrepancies between the cause of death determined on the medical data on the death extracted from the deceased patient's hospital records and the cause of death coded by the PHIC. We recommend the introduction of international coding software for coding and classification, and a review to improve data handling in hospitals, especially those with electronic patient records.

The Swedish cause of death register.

Sweden has a long tradition of recording cause of death data. The Swedish cause of death register is a high quality virtually complete register of all deaths in Sweden since 1952. Although originally created for official statistics, it is a highly important data source for medical research since it can be linked to many other national registers, which contain data on social and health factors in the Swedish population. For the appropriate use of this register, it is fundamental to understand its origins and composition. In this paper we describe the origins and composition of the Swedish cause of death register, set out the key strengths and weaknesses of the register, and present the main causes of death across age groups and over time in Sweden. This paper provides a guide and reference to individuals and organisations interested in data from the Swedish cause of death register.

Automated comparison of last hospital main diagnosis and underlying cause of death ICD10 codes, France, 2008-2009.

BACKGROUND: In the age of big data in healthcare, automated comparison of medical diagnoses in large scale databases is a key issue. Our objectives were: 1) to formally define and identify cases of independence between last hospitalization main diagnosis (MD) and death registry underlying cause of death (UCD) for deceased subjects hospitalized in their last year of life; 2) to study their distribution according to socio-demographic and medico-administrative variables; 3) to discuss the interest of this method in the specific context of hospital quality of care assessment. METHODS: 1) Elaboration of an algorithm comparing MD and UCD, relying on Iris, a coding system based on international standards. 2) Application to 421,460 beneficiaries of the general health insurance regime (which covers 70% of French population) hospitalized and deceased in 2008-2009. RESULTS: 1) Independence, was defined as MD and UCD belonging to different trains of events leading to death 2) Among the deaths analyzed automatically (91.7%), 8.5% of in-hospital deaths and 19.5% of out-of-hospital deaths were classified as independent. Independence was more frequent in elder patients, as well as when the discharge-death time interval grew (14.3% when death occurred within 30 days after discharge and 27.7% within 6 to 12 months) and for UCDs other than neoplasms. CONCLUSION: Our algorithm can identify cases where death can be considered independent from the pathology treated in hospital. Excluding these deaths from the ones allocated to the hospitalization process could contribute to improve post-hospital mortality indicators. More generally, this method has the potential of being developed and used for other diagnoses comparisons across time periods or databases.

Suicide or undetermined intent? A register-based study of signs of misclassification.

BACKGROUND: Several studies have concluded that some deaths classified as undetermined intent are in fact suicides, and it is common in suicide research in Europe to include these deaths. Our aim was to investigate if information on background variables would be helpful in assessing if deaths classified as undetermined intent should be included in the analyses of suicides. METHODS: We performed a register study of 31,883 deaths classified as suicides and 9,196 deaths classified as undetermined intent in Sweden from 1987 to 2011. We compared suicide deaths with deaths classified as undetermined intent with regard to different background variables such as sex, age, country of birth, marital status, prior inpatient care for self-inflicted harm, alcohol and drug abuse, psychiatric inpatient care, and use of psychotropics. We also performed a multivariate analysis with logistic regression. RESULTS: Our results showed differences in most studied background factors. Higher education was more common in suicides; hospitalization for self-inflicted harm was more common among female suicides as was prior psychiatric inpatient care. Deaths in foreign-born men were classified as undetermined intent in a higher degree and hospitalization for substance abuse was more common in undetermined intents of both sexes. Roughly 50% of both suicide and deaths classified as undetermined intent had a filled prescription of psychotropics during their last six months. Our multivariate analysis showed male deaths to more likely be classified as suicide than female: OR: 1.13 (1.07-1.18). The probability of a death being classified as suicide was also increased for individuals aged 15-24, being born in Sweden, individuals who were married, and for deaths after 1987-1992. CONCLUSION: By analyzing Sweden's unique high-validity population-based register data, we found several differences in background variables between deaths classified as suicide and deaths classified as undetermined intent. However, we were not able to clearly distinguish these two death manners. For future research we suggest, separate analyses of the two different manners of death.

Accuracy of death certificates of cardiovascular disease in a community intervention in Sweden.

AIM: The aim was to investigate the possibility to evaluate the mortality pattern in a community intervention programme against cardiovascular disease by official death certificates. METHODS: For all deceased in the intervention area (Norsjö), the accuracy of the official death certificates were compared with matched controls in the rest of Västerbotten. The official causes of death were compared with new certificates, based on the last clinical record, issued by three of the authors, and coded by one of the authors, all four accordingly blinded. RESULTS: The degree of agreement between the official underlying causes of death in "cardiovascular disease" (CVD) and the re-evaluated certificates was not found to differ between Norsjö and the rest of Västerbotten. The agreement was 87% and 88% at chapter level, respectively, but only 55% and 55% at 4-digit level, respectively. The reclassification resulted in a 1% decrease of "cardiovascular deaths" in both Norsjö and the rest of Västerbotten. CONCLUSIONS: The disagreements in the reclassification of cause of death were equal but large in both directions. The official death certificates should be used with caution to evaluate CVD in small community intervention programmes, and restricted to the chapter level and total populations.

Changes in statistical methods affected the validity of official suicide rates.

OBJECTIVE: This study investigates whether changes in registration and coding practices influenced official suicide rates in Norway from 1988 to 2002. STUDY DESIGN AND SETTING: A Poisson regression model was used to evaluate rates of suicide and potentially competing underlying causes of death. Setting in Norway 1988-2002. RESULTS: From 1988 to 1994, suicide mortality decreased significantly, by 23.7%. Simultaneously, rates of causes of death potentially masking suicide decreased or remained fairly stable. From 1994 to 2002, however, there were no significant changes in suicide rates but accidental poisoning, which may mask suicide, increased significantly by 32.4%. Also, "ill-defined causes" of death increased by 16.7%, indicating poorer data quality. CONCLUSION: This study suggests that the decreasing suicide rate in 1988-94 reflects a real change. However, the general quality of mortality statistics has deteriorated since the late 1990s, making it difficult to assess developments since 1994. Such variations in the reliability of official suicide statistics complicate international comparisons. However, shifts in the death rate because of "ill-defined" causes could serve as a warning that data quality is not consistent over time.

Unexplained differences between hospital and mortality data indicated mistakes in death certification: an investigation of 1,094 deaths in Sweden during 1995.

OBJECTIVE: Mortality statistics are important for epidemiological research. We examine if discrepancies between death certificate (DC) and hospital discharge condition (HDC) indicate certification errors. STUDY DESIGN AND SETTING: From 39,872 hospital deaths in Sweden in 1995, we randomly selected 600 "cases," where DC and HDC were incompatible, and 600 compatible "controls," matched on sex, age, and underlying cause of death. We obtained case summaries for 1,094 (91%) of these. Using a structured protocol, we assessed the accuracy of DCs. RESULTS: Regression analysis indicated diagnostic group and "case" or "control" as the variables that most affected the accuracy. Malignant neoplasm "controls" had the highest accuracy (92%), and benign and unspecified tumor "cases," the lowest (20%). For all diagnostic groups except one, compatible "controls" had better accuracy than incompatible "cases." The exception, chronic obstructive lung disease, had low accuracy for both "cases" (54%) and "controls" (52%). CONCLUSION: Incompatibility between DC and HDC indicates a greater risk of certification errors. For some diagnostic groups, however, DCs are often inaccurate even when DC and HDC are compatible. By requesting additional information on incompatible cases and all deaths in high-risk diagnostic groups, producers of mortality statistics could improve the accuracy of the statistics.

Methodology of studies evaluating death certificate accuracy were flawed.

BACKGROUND AND OBJECTIVE: Statistics on causes of death are important for epidemiologic research. Studies that evaluate the source data often give conflicting results, which raise questions about comparability and validity of methods. METHODS: For 44 recent evaluation studies we examined the methods employed and assessed the reproducibility. RESULTS: Thirty studies stated who reviewed the source data. Six studies reported reliability tests. Twelve studies included all causes of death, but none specified criteria for identifying the underlying cause when several, etiologically independent conditions were present. We assessed these as not reproducible. Of 32 studies that focussed on a specific condition, 21 provided diagnostic criteria such that the verification of the focal diagnosis is reproducible. Of 16 that discussed the difference between dying "with" and "from" a condition, eight described how competing causes had been handled. For these eight, the selection of a principal cause is reproducible, but in three the selection strategy conflicts with the international instructions issued by the World Health Organization. CONCLUSION: Methods and criteria are often insufficiently described. When described, they sometimes disagree with the international standard. Explicit descriptions of methods and criteria would contribute to methodologic improvement and would allow readers to assess the generalizability of the conclusions.

An international comparison study indicated physicians' habits in reporting diabetes in part I of death certificate affected reported national diabetes mortality.

BACKGROUND AND OBJECTIVE: Physicians may find it confusing to decide whether to report diagnoses in part I or part II of the death certificate. The aim of this study was to contrast differences in diabetes mortality through a comparison of physicians' habits in reporting diabetes in part I of death certification among Taiwan, Australia, and Sweden. METHODS: A cross-sectional, intercountry comparison study. We calculated the proportion of deaths with mention of diabetes in which diabetes was reported in part I of the death certificate and the proportion of deaths with mention of diabetes in which diabetes was selected as underlying cause of death. RESULTS: We found that half of the differences in reported diabetes mortality among Taiwan, Australia, and Sweden were due to differences in reporting deaths with mention of diabetes anywhere on the certificate, and half due to differences in proportion of deaths with mention of diabetes in which diabetes was reported in part I of the death certificate. CONCLUSION: Differences in the reporting of diabetes in part I of the death certificate among physicians in Taiwan, Australia, and Sweden was one of the factors that affected differing reported diabetes mortality in Taiwan, Australia, and Sweden.

Comparing hospital discharge records with death certificates: can the differences be explained?

STUDY OBJECTIVE: The quality of mortality statistics is important for epidemiological research. Considerable discrepancies have been reported between death certificates and corresponding hospital discharge records. This study examines whether differences between the death certificate's underlying cause of death and the main condition from the final hospital discharge record can be explained by differences in ICD selection procedures. The authors also discuss the implications of unexplained differences for mortality data quality. DESIGN: Using ACME, a standard software for the selection of underlying cause of death, the compatibility between the underlying cause of death and the final main condition was examined. The study also investigates whether data available in the hospital discharge record, but not reported on the death certificate, influence the selection of the underlying cause of death. SETTING: Swedish death certificates for 1995 were linked to the national hospital discharge register. The resulting database comprised 69 818 people who had been hospitalised during their final year of life. MAIN RESULTS: The underlying cause of death and the main condition differed at Basic Tabulation List level in 54% of the deaths. One third of the differences could not be explained by ICD selection procedures. Adding hospital discharge data changed the underlying cause in 11% of deaths. For some causes of death, including medical misadventures and accidental falls, the effect was substantial. CONCLUSION: Most differences between underlying cause of death and final main condition can be explained by differences in ICD selection procedures. Further research is needed to investigate whether unexplained differences indicate lower data quality.