Standardized Proportional Mortality Ratio Research Articles

Premature mortality risk in individuals with convulsive epilepsy: Results from a longitudinal, prospective, population-based study

ObjectiveTo assess premature mortality and identify associated risk factors among individuals with convulsive epilepsy in resource-poor settings using a longitudinal, prospective, population-based approach. MethodThe study recruited people with convulsive epilepsy who underwent assessment and management of epilepsy at primary healthcare centers in rural Northwest China, including newly diagnosed individuals and previously identified prevalent cases. All participants were confirmed to have epilepsy by neurologists according to strict criteria and were followed up monthly by primary care physicians. Demographic data and cause of death (COD) were obtained from death certificates or verbal autopsies conducted by neurologists, following the International Classification of Diseases, 10th Edition. The standardized mortality ratio (SMR) and proportionate mortality ratio (PMR) for each cause of death were estimated using the Cause-Of-Death Surveillance Dataset of China (2020). Survival analysis was used to identify risk factors associated with all-cause mortality and death directly due to epilepsy. ResultsDuring 5.9 years of follow-up with 40,947 person-years, there were 781 (11.2%) deaths among 6967 participants. The risk of premature death in people with convulsive epilepsy was 2.7-fold higher than that in the general population. Young participants had a significantly higher risk (standardized mortality ratio 26.5–52.5) of premature death. The proportionate mortality ratio was higher for cerebrovascular disease (15%), sudden unexpected death in epilepsy (SUDEP) (13.4%), cardiovascular disease (11.7%), status epilepsy (SE) (11.3%), and epilepsy-related accidents (14.0%) than other premature mortality cause of deaths. Additionally, the highest standardized proportional mortality ratio (SPMR) was observed from drowning in all cause of death (10.4, 95% confidence interval [CI]: 7.6–13.8), followed by burning (9.0, 95% CI: 3.7–18.9). Factors that increased the risk of all-cause mortality included male sex, late age of onset, short disease duration, high body mass index, monotherapy, and the frequency of generalized tonic-clonic seizures (GTCS). High frequency of generalized tonic-clonic seizures (> 3 attacks in the last year) was an independent risk factor for premature death directly due to epilepsy (including sudden unexpected death in epilepsy, status epilepsy, and epilepsy-related accidents), while early age of onset (≤ 14 years) and long duration of epilepsy (> 20 years) were independent risk factors for sudden unexpected death in epilepsy. In addition, short duration of epilepsy (≤ 20 years) was an independent risk factor for status epilepsy. ConclusionsThis study demonstrated that individuals with poorly controlled seizures are more likely to experience premature death, with most deaths being epilepsy-related and preventable. These findings underline the importance of effective seizure treatment and the potential impact on reducing premature mortality among people with convulsive epilepsy.

Mortality of Suicide and Cerebro-Cardiovascular Diseases by Occupation in Korea, 1997-2020.

Although studies on occupational mortality have been conducted in Korea, the results for occupations with high mortality around 2010 are inconsistent. This study aimed to examine occupational mortality from overwork-related suicide and cerebro-cardiovascular diseases (CCVD) from 1997 to 2020. We used microdata of the Causes of Death Statistics (CDS) and Economically Active Population Survey (EAPS) to obtain indirect standardized mortality ratio (SMR) and standardized proportional mortality ratio (PMR) of suicide (X60–X84) and CCVD deaths (I20–I25 and I60–I69) by gender and eight occupational categories. The trend of SMR of suicide and CCVD by occupation was similar within individual genders. The SMR of managers (MNG) was the highest for men and women in 2012–2017 and 2008–2020, respectively, whereas the SMR of professionals and related workers (PRF) was consistently low. Despite the similar socioeconomic status of MNG and PRF, we suggest that their mortality should be analyzed separately in Korea. SMR of suicide and CCVD in female MNG were consistently highest, although the PMR was low. Female MNG may have been more directly affected by the economic crisis. There is a need for work-related stress management, early intervention, and prevention policies in occupations vulnerable to mortality.

Application of Standardized Proportional Mortality Ratio to the Assessment of Health Risk in Relatively Healthy Populations: Using a Study of Cancer Risk in Telecommunication Workers with Excess Exposure to Acid Mists as an Example.

When a study population is relatively healthy, such as an occupational population, epidemiological studies are likely to underestimate risk. We used a case study on the cancer risk of workers with exposure to acid mists, a well-documented carcinogen, to demonstrate that using proportional mortality ratios (PMRs) is more appropriate than mortality ratios in assessing risk in terms of mortality. The study included 10,229 employees of a telecommunication company who worked in buildings with battery rooms. In these buildings, the battery rooms had the highest levels of sulfuric acid in the air (geometric mean = 10.7 μg/m3). With the general population in Taiwan as a reference, a decreased standardized mortality ratio (0.42, p < 0.01) from all causes combined, between 1 January 1985 and 31 December 1996, was observed, indicating a healthy worker effect. When we reanalyzed the data using standardized PMR, elevated risks were observed for all cancers combined (1.46, p = 0.01) and cancers of the digestive organs and peritoneum (1.61, p = 0.02), especially stomach cancer (2.94, p = 0.01). The results showed that PMR can detect increases in mortality when a study population is generally healthier than the comparison population and call for further studies on the possible carcinogenic effects of low-level acid mist exposures on the stomach.

Patterns of Mortality among Wisconsin Uniroyal Tire Manufacturing Workers

The goal of this analysis was to determine the patterns of mortality among deceased workers of the former Uniroyal, Inc. Plant in Eau Claire, Wisconsin, who were exposed to solvents. After collecting information on cause of death, we conducted a standardized proportional mortality ratio (PMR) and proportional cancer mortality ratio (PCMR) analysis. The results of the PCMR analysis indicate that former Uniroyal workers experienced elevated mortality due to cancers, especially lymphohematopoietic cancers, compared to other Wisconsin decedents. The former workers and family members were pursuing litigation at the time of publication. We received the list of deceased workers from plaintiffs' attorney and were compensated for conducting the analysis; the funder did not directly participate in any part of the study or influence the results. We conclude there is evidence of excess lymphohematopoietic cancer in this worker cohort.

Proportionate mortality of Italian soccer players: Is amyotrophic lateral sclerosis an occupational disease?

The objective of the study is to investigate the mortality experience of Italian soccer players and to discuss the findings in the light of possible long term effects of doping. Standardized proportionate mortality ratio (SPMR) and standardized proportionate cancer mortality ratio (SPCMR) were computed for 350 deceased subjects deriving from a list of about 24,000 active Italian soccer players from 1960 to 1996 in the three top leagues (A, B and C). When considering SPMRs, there is a substantial adherence of observed to expected mortality, with the only exception of mortality for diseases of the nervous system (13 obs. vs. 6 exp.) mainly explained by an excess of amyotrophic lateral sclerosis (8 obs. vs 0.69 exp.). As far as SPCMRs are concerned, some digestive cancers (namely: colon cancer, liver cancer and pancreas cancer) show a doubled risk. A high risk for amyotrophic lateral sclerosis is observed among Italian soccer players. Epidemiological data on association between sport and Amyotrophic Lateral Sclerosis (ALS) are contrasting. On the basis of the overall available evidence we suggest a possible connection between dietary supplements or drugs used to enhance sporting performance and ALS pathogenesis. Further epidemiological studies are needed to confirm these specific mortality risks among soccer players.

Cancer Mortality Among Japanese Immigrants and their Descendants in the State of Sao Paulo, Brazil, 1999-2001

Only a few studies on the mortality of Japanese immigrants have been conducted in Brazil despite a large population of Japanese immigrants and their different environment and lifestyle from Japanese living in Japan. To compare cancer mortality between Japanese in Japan and Japanese immigrants or Brazilians in the state of São Paulo, Brazil, we obtained official death certificates registered during 1999-2001. The standardized mortality ratio (SMR) or the standardized proportional mortality ratio (SPMR) of major cancer sites was calculated for the first generation of Japanese immigrants to Brazil (Japan-born), their Brazil-born Japanese descendants, and native Brazilians using mortality data of Japanese in Japan as a standard. The SMRs of stomach and colorectal cancer did not differ between the Japan-born residents of Brazil and the native Japanese, but significantly low SMRs were found among the native Brazilians. Compared with the native Japanese, we observed significantly lower SMRs for liver, gallbladder and lung cancer and significantly higher SMRs for prostate, cervical, and brain and nervous system cancer among both the Japan-born residents of Brazil and the Brazilians. Generally, the SPMR results were similar to those of the SMRs. Significantly high SPMRs for breast and uterine cancer were found for both the Japan- and Brazil-born residents of Brazil, although the Japan-born residents had increased SMRs, but not significantly so. We confirmed the different cancer mortality pattern in the Japanese immigrants from that in Japanese in Japan, thus demonstrating the relative importance of the environment in the development of cancer.

Nested case-control study of esophageal cancer in relation to occupational exposure to silica and other dusts.

Standardized proportionate mortality ratio (SPMR) was found to be 2.2 (95% CI = 1.3-3.5) for esophageal cancer (EC) among workers exposed to refractory brick dust in a large iron-steel complex in China. A nested case-control design within a cohort of industrial workers. One hundred and twenty-five EC cases and 250 controls were identified from the death registry file. Interviews were conducted of the next of kin for past exposure information on job, domestic, and lifestyle factors. History of occupational exposure to various dusts was reconstructed from personnel files and by interviewing colleagues utilizing a job-exposure matrix. After adjusting for confounders, occupational exposure to silica dust was the most important risk factor among all variables investigated, with a 2.8-fold risk and a clear dose-response by length of exposure. Alcohol drinking (OR = 1.8) and coal cooking (OR = 2.0) were risk factors and high consumption of fruit diet (OR = 0.5) and meat diet (OR = 0.6) were protective factors. The relationship between occupational exposure to silica dust and the risk of EC found in an earlier SPMR study was confirmed. Ingestion of silica particles after lung clearance may increase the risk of EC among workers exposed to silica.

Nested case‐control study of esophageal cancer in relation to occupational exposure to silica and other dusts

Background Standardized proportionate mortality ratio (SPMR) was found to be 2.2 (95% CI > 1.3–3.5) for esophageal cancer (EC) among workers exposed to refractory brick dust in a large iron-steel complex in China. Methods A nested case-control design within a cohort of industrial workers. One hundred and twenty-five EC cases and 250 controls were identified from the death registry file. Interviews were conducted of the next of kin for past exposure information on job, domestic, and lifestyle factors. History of occupational exposure to various dusts was reconstructed from personnel files and by interviewing colleagues utilizing a job-exposure matrix. Results After adjusting for confounders, occupational exposure to silica dust was the most important risk factor among all variables investigated, with a 2.8-fold risk and a clear dose–response by length of exposure. Alcohol drinking (OR > 1.8) and coal cooking (OR > 2.0) were risk factors and high consumption of fruit diet (OR > 0.5) and meat diet (OR > 0.6) were protective factors. Conclusions The relationship between occupational exposure to silica dust and the risk of EC found in an earlier SPMR study was confirmed. Ingestion of silica particles after lung clearance may increase the risk of EC among workers exposed to silica. Am. J. Ind. Med. 35:272–280, 1999. © 1999 Wiley-Liss, Inc.

Cancer risks among iron and steel workers in Anshan, China, Part I: Proportional mortality ratio analysis.

A standardized proportional mortality ratio (SPMR) study of 8,887 deaths during 1980-1989 among male workers in a large integrated iron-steel complex in Anshan, China, was conducted to provide clues to occupational risk factors. Accidents and cancer accounted for a higher proportion of deaths among the iron-steel workers than among the general male population (SPMR = 1.21; 95% CI = 1.12-1.31 and 1.14; 95% CI = 1.10-1.18, respectively). Among all workers, SPMRs were significantly elevated for stomach, lung, and colorectal cancers (SPMR = 1.37, 1.37, 1.38, respectively), but not other cancers. Risks of stomach cancer appeared to be highest among workers employed in jobs with exposure to iron and coal dust, whereas significant increases in colorectal cancer were seen for loading and other dusty jobs and for administrative and sedentary jobs without dust exposure. Risks of lung cancer appeared increased for a variety of jobs throughout the complex, especially those with probable high levels of exposure to polycyclic hydrocarbons and asbestos. Risk of esophageal cancer was significantly elevated for fire-resistant brick makers, and risk of nonmalignant respiratory disease was significantly elevated for those employed as furnace workers, foundry workers, and fire-resistant brick makers.

Lifestyle, environmental pollution and lung cancer in cities of Liaoning in northeastern China

<h2>Abstract</h2> Several studies were conducted in cities of Liaoning Province, one of the areas of China with heavy concentrations of industry, to investigate the effects of life-style factors and environmental pollutants on lung cancer causation. A case-control study involving 1249 lung cancer patients and 1345 population-based controls was conducted in 1985–1988 in Shenyang, the capital of Liaoning. Cigarette smoking was found to be the principal cause of lung cancer in this population, accounting for 55% of the disease in males and 37% in females. There was also a significant increase in lung cancer risk associated with an overall index of indoor air pollution due to coal-burning emission. The population attributable risk (PAR) for indoor air pollution was 13% for males and 17% for females. Risks were significantly increased for workers in the non-ferrous smelter (odds ratio (OR) = 2.6, 95% CI, 1.3–5.1), chemical and drug manufacturing (OR = 3.0, 95% CI, 1.0–8.0), and the glass and pottery industry (OR = 1.6, 95% CI, 1.0–2.5). Studies in the Anshan Iron-Steel Complex showed a significant excess of lung cancer for workers exposed to a variety of dusts. A standardized proportional mortality ratio (SPMR) study of 8887 deaths during 1980–1989 among male workers of the complex indicated a 37% excess risk of lung cancer compared to residents of the city. A nested case-control study was then conducted in that complex. A total of 610 cases of lung cancer diagnosed during 1987–1993 and 959 randomly selected controls from 196993 active and retired employees of the complex were interviewed. Historical monitoring records for dust and benzo(<i>a</i>)pyrene (B(<i>a</i>)P) were collected from 1956–1992 to calculate cumulative exposure for each person. Results suggested that risks were increased for all occupations in which there was exposure to dusts, with the highest risks seen among coke oven workers (OR = 3.5, 95% CI, 2.0–6.4) and fire-resistant brick makers (OR = 2.9, 95% CI, 1.9–4.4). Significant dose-response patterns between cumulative total dust, cumulative total B(<i>a</i>)P and lung cancer risk were observed. The findings suggest that smoking and environmental pollution combine to account for elevated rates of lung cancer in cities of northeastern China.

Lifestyle, environmental pollution and lung cancer in cities of Liaoning in northeastern China

Several studies were conducted in cities of Liaoning Province, one of the areas of China with heavy concentrations of industry, to investigate the effects of life-style factors and environmental pollutants on lung cancer causation. A case-control study involving 1249 lung cancer patients and 1345 population-based controls was conducted in 1985–1988 in Shenyang, the capital of Liaoning. Cigarette smoking was found to be the principal cause of lung cancer in this population, accounting for 55% of the disease in males and 37% in females. There was also a significant increase in lung cancer risk associated with an overall index of indoor air pollution due to coal-burning emission. The population attributable risk (PAR) for indoor air pollution was 13% for males and 17% for females. Risks were significantly increased for workers in the non-ferrous smelter (odds ratio (OR) = 2.6, 95% CI, 1.3–5.1), chemical and drug manufacturing (OR = 3.0, 95% CI, 1.0–8.0), and the glass and pottery industry (OR = 1.6, 95% CI, 1.0–2.5). Studies in the Anshan Iron-Steel Complex showed a significant excess of lung cancer for workers exposed to a variety of dusts. A standardized proportional mortality ratio (SPMR) study of 8887 deaths during 1980–1989 among male workers of the complex indicated a 37% excess risk of lung cancer compared to residents of the city. A nested case-control study was then conducted in that complex. A total of 610 cases of lung cancer diagnosed during 1987–1993 and 959 randomly selected controls from 196993 active and retired employees of the complex were interviewed. Historical monitoring records for dust and benzo( a)pyrene (B( a)P) were collected from 1956–1992 to calculate cumulative exposure for each person. Results suggested that risks were increased for all occupations in which there was exposure to dusts, with the highest risks seen among coke oven workers (OR = 3.5, 95% CI, 2.0–6.4) and fire-resistant brick makers (OR = 2.9, 95% CI, 1.9–4.4). Significant dose-response patterns between cumulative total dust, cumulative total B( a)P and lung cancer risk were observed. The findings suggest that smoking and environmental pollution combine to account for elevated rates of lung cancer in cities of northeastern China.

Cancer mortality among japanese residents of the city of säo paulo, Brazil

Death certificates of Japanese residents of the city of São Paulo, Brazil from 1979 to 1981 were analyzed for cancer deaths by means of the standardized mortality ratio (SMR) and the standardized proportional mortality ratio (SPMR). Compared with residents of Japan, a significantly higher SMR value was obtained from Japan-born residents of São Paulo for prostate cancer, whereas lower values were obtained for cancer of the liver and gall-bladder in both sexes, of the esophagus and rectum in males, and of the lung in females. SMR values were higher for cancer of the stomach in both sexes but lower for those of the esophagus and prostate in males and of the gall-bladder and breast in females, when compared with the general population of São Paulo. Among Japan- and Brazil-born residents, stomach cancer in women revealed a significant stepwise decrease by generation when SPMR was used as an indicator. The high proportion of stomach cancer in males, however, was as high among the Brazil-born generation as in Japan. The SPMR of liver cancer decreased to the low level of the general population of São Paulo, even among the first generation. These changes in cancer patterns are discussed in relation to those among Japanese residents in the United States.

Comportamiento de indicadores de mortalidad en áreas geográficas pequeñas: razón de mortalidad estandarizada relativa y razón de mortalidad proporcional estandarizada

One of the most commonly used indicators in mortality studies is the Standardized Mortality Ratio (SMR) being the Relative Standardized Mortality Ratio (RSMR) an indicator of the relative magnitude of the SMR for a specific cause of death. Along with these indicators, which must be calculated by using the population at risk, there is the Standardized Proportional Mortality Ratio (SPMR), an indicator which measures the excess mortality referring to the proportional mortality established for a standard population. This paper reviews the theoretic conditions described in literature as being necessary to establish a probability interval for the RSMR centered on the SPMR as well as the correlations between both indicators and the use of the SPMR as a predictor of the RSMR. The results obtained clearly show how difficult it is for these theoretic conditions to exist. However, they do suggest that the SPMR be used as a predictor of RSMR.

Mortality odds ratio, proportionate mortality ratio, and healthy worker effect

The standardized proportionate mortality ratio (PMRi) and the mortality odds ratio (MORi) are two statistics used to approximate the cause specific standardized mortality ratio (SMRi) when death data are available but the population at risk is not known. When there is a healthy worker effect, the MORi will always overestimate the SMRi and will always be greater than the PMRi. The PMRi is influenced by the relative frequency of the cause of death. For rare causes, such as brain cancer or leukemia, the PMRi will overestimate the SMRi to essentially the same degree as the MORi. For more common conditions, such as lung cancer, the PMRi will overestimate or underestimate the SMRi depending on the magnitude of the healthy worker effect. When the SMRi = 1 and there is a healthy worker effect, both the PMRi and MORi are in excess of one (1) regardless of the disease rate. As the SMRi increases it is more likely to be bounded by the PMRi (lower) and the MORi (upper). We therefore recommend that each statistic be derived when death certificates are the only source of data used to assess risk due to occupational exposures.

Prediction of the Standardized Risk Ratio via Proportional Mortality Analysis

AbstractThe relationship between the commonly used indiréctly standardized comparative mortality indices, the standardized mortality ratio (SMR) and the standardized proportional mortality ratio (SPMR) is well known; whereas, the relationship between their less commonly used directly adjusted counterparts, the standardized risk ratio (SRR) and the recently proposed externally standardized proportional mortality ratio (SePMR) has been heretofore not developed. This paper fills this void by demonstrating the algebraic and statistical relationship between the SRR and the SePMR and showing how, under some modest assumptions, valid inferences about the SRR can be based on analysis of SePMR's. More specifically, an asymptotic prediction interval has been developed for the SePMRi which, with high probability, contains the ratio RSRRi = SRRi/SRR. The utility of the SePMRi is supported empirically using data from a recent retrospective cohort study of mineral fiber workers.

The measurement and interpretation of proportionate mortality.

The standardized proportionate mortality ratio (SPMR) is shown to be a summary measure which is a weighted average of age-specific proportionate mortality ratios which uses an internally derived set of standard weights. As with any summary measure, the SPMR is only meaningful when the stratum-specific values can be judged to represent a common value. When stratum-specific values are not homogeneous, the use of the stratum-specific values themselves is more appropriate than the use of a summary measure. A test for homogeneity of the age-specific proportionate mortality ratios is presented. The test also provides an estimate of the common value and its variance, when that single parameter can be presumed to exist. A procedure of external standardization is presented which uses weights derived from the standard population.

On the utility of proportional mortality analysis

The Standardized Mortality Ratio (SMR) is a commonly used epidemiologic tool for evaluating a test population with respect to a standard. Computation of the measure requires that the size and demographic composition of the test population-at-risk (PAR) be known. In the absence of this knowledge of the PAR, some have turned to evaluations based on proportional mortality rates, a method which is generally regarded as deficient because of the inability of relative measures to provide information about absolute rates. Often, the ratio of the cause-specific SMR to the underlying ‘force of mortality’ (i.e. the SMR for all causes) is of interest; this ratio is referred to herein as the relative SMR (RSMR). It is shown in this paper, both empirically and in a theoretical framework, that the RSMR is close in value to the (age) standardized proportional mortality ratio (SPMR), this closeness being expressible in the form of a ‘confidence interval’ involving the SPMR. Computation of the SPMR does not require knowledge of the PAR.