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PubMed2000

The influence of weather on human mortality in Hong Kong.

This study is the first attempt to investigate mortality seasonality and weather-mortality relationships in Hong Kong from 1980 to 1994. Monthly mortality data from all causes of death, neoplasm, circulatory and respiratory diseases were obtained from the Census and Statistics Department and the weather data were obtained from the Hong Kong Observatory. Regression analyses and ANOVA were employed. Significant winter peaks in sex specific and total deaths from all causes, circulatory and respiratory diseases were ascertained. Cancer mortality, however, was not seasonal. Mortality seasonality only existed in age groups 45-64 and > or =65. For the impact of weather on mortality, no significant relationship between weather variables and cancer mortality was observed. A significant negative association between minimum temperature and a positive relationship between cloud and deaths were found. This suggests that colder and cloudy conditions may heighten mortality. Wind was discovered to have a negative association with mortality. This finding revealed that the stressful effect of wind on mortality was negligible. There was no apparent sex difference. Deaths from the younger age groups (0-24 yr old) were not weather related. Weak weather connection with mortality for age group 25-44 was discovered, with Adj r2 values ranging from 0.05 to 0.07. The elderly (age > or =65) were more vulnerable to weather stress and strong weather-mortality relationship was uncovered, with Adj r2 values from 0.36 to 0.66. These results are important information for formulating public health policies.

Age Distribution↗
PubMed2003

Short-term, intermediate-term, and long-term mortality in patients hospitalized for stroke.

Cerebrovascular disease is the third leading cause of death and the primary cause of long-term disability in the United States. Although the risk factors for stroke have been well defined, less is known about stroke mortality over varying time periods within the same cohort of patients. The purpose of this study is to define rates of short-term, intermediate-term, and long-term stroke mortality among patients experiencing a first-ever hemorrhagic or ischemic stroke between 1994 and 1998. Patients were identified from the Patient Treatment Files of the Department of Veterans Affairs (VA). We included all patients who were discharged from a VA inpatient facility with a diagnosis of acute stroke. Patients were excluded from the study if they had an admission within the previous 5 years for stroke or hemiplegia. We obtained information on the patient's age, gender, and coexisting illnesses. Unadjusted and adjusted 30-day mortality rates were computed using Kaplan-Meier analyses and Cox proportional hazards regression models. The survival-dependent Cox proportional hazards regression models were run for 31-90 days and 91-365 days from the index admission date, for patients who had survived to the start of each of these time periods. Separate models were run for ischemic (n = 34,866 patients) and hemorrhagic (n = 5,442 patients) strokes. Unadjusted 30-day mortality was 8.2 and 20.5% for ischemic and hemorrhagic strokes, respectively. The adjusted 30-day mortality rate was 7.4 and 18.8% for ischemic and hemorrhagic strokes, respectively. For ischemic stroke, age 65 years and older was associated with an increased risk for short-term, intermediate-term, and long-term mortality, while chronic heart failure was associated with an increased risk for short-term and long-term mortality. For hemorrhagic stroke, age 75 years and older, malignancy, and chronic heart failure were associated with increased mortality during all three time periods. Thirty-day mortality is over two times greater following hemorrhagic stroke vs. ischemic stroke. For patients who survive 30 days after an ischemic stroke, the risk factor that remains significantly associated with long-term mortality, which may be improved with appropriate process of care, is chronic heart failure. For patients with a hemorrhagic stroke, variables that remain significantly associated with increased short-term and long-term mortality include malignant neoplasm and chronic heart failure. Information on stroke mortality is important for patients, physicians, and researchers. In addition to stroke treatment, clinicians must be able to provide families of stroke victims with appropriate prognostic information. Further work is needed to assess the impact of actual care patterns, for the above identified risk factors, on stroke prognosis over varying time periods.

Adult↗
PubMed2006

Mortality after bilateral salpingo-oophorectomy in BRCA1 and BRCA2 mutation carriers: a prospective cohort study.

BACKGROUND: Bilateral prophylactic salpingo-oophorectomy (BPSO) is used widely used to reduce the risk of breast and ovarian cancer in women with BRCA1 and BRCA2 mutations. However, the reduction in mortality after this surgery is unclear. We aimed to assess whether BPSO improves overall mortality or cancer-specific mortality in BRCA1 and BRCA2 mutation carriers. METHODS: We identified a prospective cohort of 666 women with disease-associated germline mutations in BRCA1 or BRCA2 and no previous cancer diagnosis. In our primary analysis, we compared 155 women who had had BPSO and 271 women matched for age at BPSO who had not had BPSO. In our secondary analysis, we compared 188 women who had had BPSO with 478 women who had not. In both analyses, we compared overall mortality and cancer-specific mortality. All analyses were adjusted for centre, mutation (BRCA1 vs BRCA2), and birth year. FINDINGS: In the primary analysis, mean follow-up from BPSO to censoring was 3.1 years [SD 2.4] in the BPSO group and 2.1 years [2.0] in the non-BPSO group. The hazard ratio (HR) for overall mortality was 0.24 (95% CI 0.08-0.71), for breast-cancer-specific mortality was 0.10 (0.02-0.71), and for ovarian-cancer-specific mortality was 0.05 (0.01-0.46) for women who had BPSO compared with those who had not. In secondary analysis, BPSO was associated with reduced overall mortality (HR 0.28 [95% CI 0.10-0.74]), but not with breast-cancer-specific mortality (0.15 [0.02-1.18] or ovarian-cancer-specific mortality (0.23 [0.02-1.87]. When regarded as a time-dependent covariate, BPSO was not associated significantly with mortality. INTERPRETATION: If confirmed, the finding that BPSO improves overall survival and cancer-specific survival in women with BRCA mutations will complement our existing knowledge of cancer-risk reduction associated with BPSO. Together, these data could give information to women who are considering genetic testing.

Adult↗
PubMed2005

Is education associated with mortality for breast cancer and cardiovascular disease among black and white women?

BACKGROUND: Although low socioeconomic status (SES) has been found to be an important risk factor for all-cause mortality in women, the association is inconsistent across specific causes of death. SES appears to have different associations with 2 common causes of mortality in women: low SES is associated with greater cardiovascular disease (CVD) mortality in women but may also be associated with lower breast cancer mortality. OBJECTIVE: We examined the association between SES and CVD and breast cancer mortality among black and white women. METHODS: Our analysis sample included black and white women participating in the National Longitudinal Mortality Study, which links US Census Bureau Current Population Surveys with the National Death Index between 1979 and 1989. Education and income were used as SES indicators. For each cause of death, we used multivariate logistic regression to estimate variation in mortality risk across SES levels within each racial group. RESULTS: The sample included 21,303 black women and 186,322 white women. Unadjusted cumulative incidence (over a mean follow-up period of 8.7 years) of CVD mortality was 4.2% among black women and 2.3% among white women, and of breast cancer mortality was 0.3% among black women and 0.4% among white women. After adjustment for age, marital status, and urban or rural residence, less education was still associated with greater CVD mortality among black women (odds ratio [OR], 1.8; 95% Cl, 1.03-3.0) and white women (OR, 1.4; 95% Cl, 1.3-1.6). However, less than a high school education was associated with lower breast cancer mortality among white women (OR, 0.73; 95% CI, 0.6-0.9) but not among black women (OR, 1.1; 95% Cl, 0.5-2.3). Similar ORs were obtained when income was examined. CONCLUSIONS: The association between SES and cause-specific mortality may differ between black and white women for breast cancer death but not CVD death. Better understanding of these inter actions could guide the targeting of more effective interventions.

Adult↗
PubMed2003

Relative and absolute gender gap in all-cause mortality in Europe and the contribution of smoking.

This paper examined whether international variations in absolute and relative gender differences in mortality are related to the overall mortality rates, and whether the international variation in gender gap in mortality can in part be explained by smoking. I used data on mortality from all causes in 32 European countries published by the World Health Organisation, and indirect estimates of mortality attributable to smoking in the age band 35-69 years by Peto et al. The main analyses were restricted to the age band 35-69 years but results for mortality at all ages were virtually identical. The overall mortality rates (both sexes combined) were strongly related to absolute gender differences (r = 0.91) but only weakly to relative differences (r = 0.35). The gender gap was larger in eastern than in western Europe for rate differences (1005 vs. 530 per 100,000, respectively), but it was similar for rate ratios (2.3 vs. 2.1, respectively). Both absolute and relative gender differences in mortality were strongly related to the difference between men and women in the proportion of all deaths attributed to tobacco (partial correlations, after controlling for the overall death rates, were 0.59 and 0.66, respectively). Excluding tobacco-related deaths attenuated the associations between the overall mortality rates with absolute differences (r = 0.70) and reduced the difference in the absolute gender gap between eastern and western Europe. More importantly, excluding tobacco-related deaths eliminated entirely the association with relative differences (r = -0.15) as well as any suggestion that the relative gender gap is larger in eastern than in western Europe. These results show that tobacco plays an important role in generating international differences in the size of gender gap in mortality. The much discussed association between' the overall life expectancy and the gender gap in life expectancy is a numerical product of absolute death rates (differences in life expectancy are driven by differences in rates). The association of overall mortality with male/female mortality ratios is much weaker.

Adult↗
PubMed1996

The dose of hemodialysis and patient mortality.

The relationship between the delivered dose of hemodialysis and patient mortality remains somewhat controversial. Several observational studies have shown improved patient survival with higher levels of delivered dialysis dose. However, several other unmeasured variables, changes in patient mix or medical management may have impacted on this reported difference in mortality. The current study of a U.S. national sample of 2,311 patients from 347 dialysis units estimates the relationship of delivered hemodialysis dose to mortality, with a statistical adjustment for an extensive list of comorbidity/risk factors. Additionally this study investigated the existence of a dose beyond which more dialysis does not appear to lower mortality. We estimated patient survival using proportional hazards regression techniques, adjusting for 21 patient comorbidity/risk factors with stratification for nine Census regions. The patient sample was 2,311 Medicare hemodialysis patients treated with bicarbonate dialysate as of 12/31/90 who had end-stage renal disease for at least one year. Patient follow-up ranged between 1.5 and 2.4 years. The measurement of delivered therapy was based on two alternative measures of intradialytic urea reduction, the urea reduction ratio (URR) and Kt/V (with adjustment for urea generation and ultrafiltration). Hemodialysis patient mortality showed a strong and robust inverse correlation with delivered hemodialysis dose whether measured by Kt/V or by URR. Mortality risk was lower by 7% (P = 0.001) with each 0.1 higher level of delivered Kt/V. (Expressed in terms of URR, mortality was lower by 11% with each 5 percentage point higher URR; P = 0.001). Above a URR of 70% or a Kt/V of 1.3 these data did not provide statistical evidence of further reductions in mortality. In conclusion, the delivered dose of hemodialysis therapy is an important predictor of patient mortality. In a population of dialysis patients with a very high mortality rate, it appears that increasing the level of delivered therapy offers a practical and efficient means of lowering the mortality rate. The level of hemodialysis dose measured by URR or Kt/V beyond which the mortality rate does not continue to decrease, though not well defined with this study, appears to be above current levels of typical treatment of hemodialysis patients in the U.S.

Female↗
PubMed2002

One-year mortality among unselected outpatients with heart failure.

OBJECTIVE: To estimate 1-year mortality and prognostic factors in unselected outpatients with heart failure, and to compare the observed mortality with the estimates of the primary care physicians. METHODS AND RESULTS: Four hundred and eleven consecutive patients with heart failure New York Heart Association (NYHA) class II-IV (mean population age 75 years, 56% males) were enrolled in 71 primary care offices throughout Switzerland. During a mean follow-up period of 1.4 years, 68 patients had died. One-year total mortality was 12.6% compared to 4.3% in the underlying Swiss population (standardized mortality ratio 3.0). Among patients with heart failure NYHA II, III and IV, mortality was 7.1%, 15.0% and 28.0%, respectively. In multivariate Cox regression, statistically significant (P<0.05) predictors of mortality were NYHA class (NYHA III: risk ratio [RR]=1.6; NYHA IV: RR=2.2), recent hospital stay for heart disease (RR=2.3), creatinine>120 micromol.l(-1) (RR=1.8) systolic blood pressure<100 mmHg (RR=2.4), heart rate>100 min(-1) (RR=2.7), age (per 10 years, RR=1.6) and female gender (RR=0.49). Among patients with reduced left ventricular ejection fraction, 1-year mortality was 14.3%, and predictors were similar except that female gender was no longer associated with reduced mortality. Primary care physicians significantly overestimated 1-year mortality (estimated mortality 25.9% vs observed mortality 12.6%,P =0.001). CONCLUSIONS: Unselected outpatients with heart failure have a poor prognosis, particularly those with advanced heart failure and a recent hospital stay for heart disease. Primary care physicians are aware of the high mortality of this growing patient population.

Aged↗
PubMed1993

The epidemiology of peptic ulcer mortality 1953-1989: a birth cohort analysis.

Peptic ulcer (PU) disease is the cause of substantial morbidity and mortality in a number of countries including Australia. Despite diagnostic and treatment advances, sustained mortality from PU disease has been reported. To understand this problem a birth cohort analysis using the Median Polish Technique (MPT) was performed on 36 years of mortality data from New South Wales, Australia. The MPT allows cohort effects to be quantified, yet has rarely been applied to mortality data. Birth cohort effects detected using graphical presentation of mortality data for duodenal (DU) and gastric ulcer (GU) mortality data for both males and females, were supported by the results obtained using the MPT. The DU mortality rates for females increased significantly over the 36-year period. This increase can be explained by the presence of a birth cohort effect, with women born between 1898 and 1913 having a greater risk of dying from DU than preceding or subsequent generations. Cohort effects in GU and DU mortality data for males and in GU mortality for females were also present, although these were masked by the overall decline in PU mortality rates. The results support the findings of other studies of birth cohort effects in PU mortality data from England, Europe and Japan, and provide support for the existence of environmental factors which resulted in increased PU mortality among specific birth cohorts. Demonstration of these birth cohort effects should influence the theories of PU disease aetiology and prevention and should be considered in developing approaches for further research.

Aged↗
PubMed2001

Competing risks analysis using Markov chains: impact of cerebrovascular and ischaemic heart disease in cancer mortality.

BACKGROUND: A decrease in cerebrovascular disease (CVD) and ischaemic heart disease (IHD) mortality can produce an increase in mortality from other causes, even cancer. This problem is called the competing risks problem. METHODS: A Markov chain is used to analyse the interrelation between CVD, IHD and cancer mortalities in Spanish women in 1981 and 1994. We compare the results using two models: discarding CVD and IHD mortality (the elimination model) and substituting CVD and IHD 1981 mortality rates in 1994 figures (the constant model). RESULTS: Removing mortality from CVD and IHD increases cancer mortality rates in women aged > or = 70, and the probability of death from cancer rises from 10.7% to 13.3%. In the second model, the use of CVD and IHD 1981 mortality rates in 1994 data yields slightly lower mortality rates and so the impact of CVD and IHD mortality changes in the period 1981 to 1994 is negligible except in elderly women. CONCLUSIONS: Although IHD and CVD mortality have decreased in all age groups of Spanish women from 1981 to 1994, this has not had a great impact on cancer mortality.

Adult↗
PubMed2005

Cause-specific mortality in old age in relation to body mass index in middle age and in old age: follow-up of the Whitehall cohort of male civil servants.

BACKGROUND: The relevance of body mass index (BMI) to cause-specific mortality in old age is uncertain. OBJECTIVES: To examine cause-specific 5 year mortality in old age by BMI in old age and middle age (40-69 years). METHODS: Cox proportional hazards for mortality rates among 4862 former male civil servants in relation to quartiles of BMI measured when screened in 1968-70 and when resurveyed in 1997-98 (median age 76 years). RESULTS: The association between all-cause mortality after resurvey and BMI in old age was U-shaped with hazard ratios (HRs) of 1.3 (95% CI 1.1-1.5) for the lightest and heaviest categories relative to the middle two. Among 'healthy' men the lightest (<22.7 kg/m2) had greatest all-cause mortality. The heaviest men (>26.6 kg/m2) had increased risk of cardiovascular disease (CVD) mortality in the first two years or for the whole period if never-smokers. Respiratory mortality was inversely associated with BMI in old age [adjusted HR for trend per BMI category increase 0.6 (0.5-0.7)] but cancer mortality lacked a clear pattern. Net gain or loss of 10 kg or more between middle and old age was a strong predictor of all-cause and CVD mortality. CONCLUSIONS: The shape of the association between BMI in old age and mortality differs by cause of death. Major weight change over time is a warning signal for higher CVD mortality. Having BMI<22.7 kg/m2 in old age is associated with above-average mortality rates even if apparently healthy.

Aged↗
PubMed2006

Socioeconomic differentials in cause-specific mortality among South Korean adolescents.

BACKGROUND: There is inconsistent evidence regarding the presence of a socioeconomic differential in adolescent all-cause and cause-specific mortality. This study examines possible socioeconomic mortality differentials in Korean adolescents. Method A total of 330 321 boys and 311 830 girls aged 10-19, who are health insurance beneficiaries for civil servants and private school teachers of Korean Health Insurance Cooperation, were followed for 9 years (1995-2003). Parental income information was linked to national death certificate data. RESULTS: For boys, all-cause mortality showed a graded inverse relationship with income level in both 10-14 year olds (RR = 1.64, 95% CI: 1.40-1.91) and 15-19 year olds (RR = 1.68, 95% CI: 1.40-1.91). The major contributor was mortality differentials from external causes, with differentials of transport accident death the most important. Mortality from circulatory disease was higher in the lowest income groups in 15-19 year olds (RR = 2.21, 95% CI: 1.09-4.50). A significant socioeconomic gradient of non-external cause mortality was found in 15-19 year olds. For girls, socioeconomic differentials were less evident than boys. The all-cause mortality gradient for girls was smaller than for boys and only significant between the lowest and the highest tertile in both 10-14 year olds and 15-19 year olds (RR = 1.33, 95% CI: 1.02-1.72, RR = 1.38, 95% CI: 1.11-1.72, respectively). There were significant socioeconomic mortality differentials in all external causes and transport accidents and a marginally significant difference in suicide mortality for 10-19 year olds. Mortality from non-external causes showed no social gradient in girls. CONCLUSIONS: Socioeconomic differentials in all-cause mortality were observed in adolescents, even in early youth. This pattern might also apply to mortality from non-external causes, especially cardiovascular disease in 15-19 year old males.

Accidents↗
PubMed1994

Temporal patterns in colorectal cancer incidence, survival, and mortality from 1950 through 1990.

BACKGROUND: Colorectal cancer mortality rates among U.S. white males remained relatively constant from 1950 through 1984 but declined sharply from 1985 through 1990. Those for U.S. white females decreased consistently from 1950 through 1984, with an acceleration of the decline from 1985 through 1990. PURPOSE: A study was planned to investigate patterns in incidence, survival, and mortality rates over time in order to examine possible reasons for the gender difference in mortality trends and for the decrease in the slope of the mortality trends for both males and females in the late 1980s. METHODS: Incidence and survival data from the Connecticut Cancer Registry were examined to investigate the gender differences in mortality rates from 1950 through 1984. Incidence and survival data from the Surveillance, Epidemiology, and End Results (SEER) Program were investigated to examine reasons for the abrupt downturn in mortality rates for both white males and white females beginning around 1985. RESULTS: During the period 1950 through 1984, the colorectal cancer incidence rates in Connecticut increased for males and declined slightly for females. Survival rates were similar for both sexes, increasing on average over 1% per year for both females and males from 1950 through 1984. Examination of SEER data from 1975 through 1990 revealed that for both males and females there were 1) declines in overall incidence and mortality rates beginning in the mid-1980s, 2) steady declines in distant disease incidence rates since 1975, 3) increases in regional disease incidence rates until the early 1980s followed by declines in the late 1980s, and 4) increases in local disease incidence rates until the mid-1980s followed by declines in the late 1980s. Age-period-cohort analyses of mortality rates indicated a statistically significant moderation of colorectal cancer risk with both advancing birth cohorts and recent calendar periods. CONCLUSIONS: The gender differences in colorectal cancer mortality rate trends observed from 1950 through 1984 are due to differences in incidence rate trends between males and females. Declining colorectal mortality rates in the late 1980s for males and females appear to reflect improved early detection. The peaking and subsequent decline of stage-specific incidence rates at later years for successively lower stage indicate sequential stage shifts as cancers are detected increasingly earlier over time. The increased use of sigmoidoscopy and fecal occult blood tests (triggering colonoscopy) appears to have played an important role in reducing colorectal cancer mortality. Improvements in birth cohort trends in risk for colorectal cancer for each sex suggest that lifestyle changes may have also contributed to the steady reductions in colorectal cancer mortality.

Adult↗
PubMed1998

Mortality and causes of death of 344 Danish patients with systemic sclerosis (scleroderma)

OBJECTIVE: To determine survival, mortality and causes of death in Danish patients with systemic sclerosis (scleroderma), and to analyse how these parameters are influenced by demographic variables and the extent of skin involvement. METHODS: A cohort of 344 patients with incident systemic sclerosis (SSc) after 1 January 1960 was retrospectively identified, representing 3716 patient-years of follow-up. The vital status at the end of the study ultimo 1996 was established by reviewing the clinical charts and by contacting the Danish Central Person Register. The causes of death were based on information obtained from the hospital charts and the autopsy reports (80%) and death certificates (20%). The extent of skin sclerosis was described by means of a two-subset model (limited and diffuse involvement) and a three-subset model (digital, extremity and truncal involvement) in all patients. Expected numbers of deaths were calculated by means of age- and sex-specific mortality rates of the general Danish population. RESULTS: Crude mortality rates were 6.5 and 3.9%/yr, respectively, in men and women. The standardized mortality ratio (SMR) was 2.9 (95% CI 2.5-3.4) and was not significantly influenced by sex or age at disease onset. Mortality rates were significantly increased in patients with diffuse skin sclerosis (SMR 4.5, 95% CI 3.5-5.7) and patients under the age of 35 yr (SMR 13, 95% CI 2.7-37). Of the 160 patients who died during the study, 41 deaths (26%) were SSc related, accounting for one-third of the excess mortality. CONCLUSION: We found a significantly increased mortality in patients with SSc, particularly in the subset of patients with diffuse skin sclerosis and in young patients. The excess mortality was due to an increase in both the SSc-related mortality and the unrelated mortality. However, all other subsets also had a significantly increased risk of death, mainly due to an increased risk of death due to causes unrelated to SSc, cancer among others. The fact that the unrelated mortality in SSc was found to be 2-fold increased suggests that the excess mortality that was classified as unrelated should more appropriately be termed indirectly SSc related.

Adolescent↗
PubMed2006

Differences in breast cancer mortality worldwide: unsolved problems.

Breast cancer mortality remains a major cause of female mortality. Between 1970 and 2000 both important increases and decreases in breast cancer mortality rates occurred. Large differences in breast cancer mortality exist among countries worldwide. Contradictory findings concerning the role of lifestyle, especially nutrition, remain to be explained. Possible explanations for the observed mortality differences will be explored. Breast cancer mortality rates have been correlated with other causes of mortality; both cancer and noncancer, using data obtained from 47 countries worldwide (World Health Organization). They have also been correlated with dietary data, especially concerning fat (animal and vegetal) intake (Food and Agricultural Organization). Highly significant correlations existed between breast cancer mortality and mortality from other cancers (e.g. colon, stomach) obtained from both sexes. These correlations have been confirmed over a period of more than 40 years. Highly significant positive correlations also existed with the intake of animal (saturated) fat, covering a period of 30 years. In multivariate regression, only the relationship with the colon, prostate cancer and total energy intake remained significant. Ecological data point to nutritional factors, especially animal fat, as major promoters of breast cancer mortality worldwide. This contrasts with the results of most cohort studies. These contradictory results and the relationship between breast cancer mortality and other causes of mortality remain to be explained. More refined and standardized dietary data are necessary.

Aged↗
PubMed2004

Perinatal mortality in first- and second-born twins in the United States.

OBJECTIVE: To evaluate the prevailing mortality paradox that second-born twins are at higher risk of perinatal mortality than first-born twins. METHODS: We used the 1995-1997 United States "matched multiple birth" data files assembled by the National Center for Health Statistics, for analysis of risk of perinatal mortality in first- and second-born twins (293788 fetuses). Perinatal mortality was defined to include stillbirths after 20 weeks of gestation and neonatal deaths (deaths within the first 28 days). Gestational age-specific risk of perinatal mortality (per 1000 total births), stillbirth (per 1000 total births), and neonatal mortality (per 1000 livebirths) by order of twin birth were based on the fetuses-at-risk approach. Associations between order of birth and mortality indices were evaluated by fitting multivariable logistic regression models based on the method of generalized estimating equations. These models were adjusted for several potential confounding factors. RESULTS: Perinatal mortality was 37% higher in second-born (26.1 per 1000 total births) than in first-born (20.3 per 1000 total births) twins (adjusted relative risk [RR] 1.37; 95% confidence interval [CI] 1.32, 1.42). The increased risk of perinatal mortality in second-born twins was chiefly driven by a 2.46-fold (95% CI 2.29, 2.63) increase in the number of stillbirths. However, the risk of neonatal mortality was very similar between first- and second-born twins (RR 0.99, 95% CI 0.95, 1.04). CONCLUSIONS: The increased risk of perinatal death in second-born twins is driven chiefly by increased rates of stillborn second twins. Thus, the increased mortality in second-born over first-born twins probably is an artifact of mortality comparisons.

Adult↗
PubMed2002

On the evolution of virulence and the relationship between various measures of mortality.

Smallpox causes roughly 20% mortality whereas chickenpox causes less than 0.1%. Most 'verbal' (i.e. non-mathematical) discussions using a mortality definition of virulence would therefore label smallpox as more virulent. Indeed, the virulence of many diseases is measured using such case mortalities, chi, or related measures such as expected host lifespan, T, or lethal dose, LD(x). But chi, T and LD(x) are only indirectly related to parasite-induced instantaneous mortality rate, alpha, which is the mortality measure used in much of the theory developed to explain virulence evolution. Here I point out that relatively deadly pathogens can actually have lower values of alpha than benign pathogens, demonstrating that alpha does not, by itself, reflect the extent to which a parasite causes host mortality. I present mathematical relationships between alpha and chi, T and LD(x), and use these to demonstrate that predictions about virulence evolution can be qualitatively altered depending upon which measure is used as the definition of virulence. Two simple examples are presented to illustrate this point, one of which demonstrates that the well-cited prediction that virulence should evolve to be higher when disease-independent host mortality increases need not hold. This prediction has been made in terms of parasite-induced instantaneous mortality, alpha, but if virulence is measured using case mortality (or T or LD(x)) then this prediction can easily be reversed. Theoretical and empirical researchers must use compatible mortality measures before a productive exchange between the two can take place, and it is suggested that case mortality (or lethal dose) is best suited as a single (mortality) measure of parasite virulence.

Biological Evolution↗
PubMed2006

Comparison of the possum, P-POSSUM and Cr-POSSUM scoring systems as predictors of postoperative mortality in patients undergoing major colorectal surgery.

BACKGROUND: Physiologic and operative severity score for the enumeration of mortality and morbidity (POSSUM), 'Portsmouth'-physiologic and operative severity score for the enumeration of mortality and morbidity (P-POSSUM) and 'Colorectal'-physiologic and operative severity score for the enumeration of mortality and morbidity (Cr-POSSUM) are three related scoring systems, which uses individual patient parameters to predict postoperative mortality. POSSUM overpredicts mortality in low-risk patients and underpredicts mortality in elderly and emergency patients. P-POSSUM was developed to compensate for these weaknesses. Cr-POSSUM was developed specifically for colorectal surgery. We aim to establish which of these scoring systems would be most useful in an Australasian context. METHODS: Data were collected for 308 patients and predicted mortality risk values were generated using each of the three systems. The Mann-Whitney U-test was then carried out on the scores for each system. Receiver-operator characteristic curves were designed to determine the relative accuracy of each approach at discriminating between death and survival. RESULTS: All three POSSUM scoring systems showed a statistically significant ability to predict postoperative mortality. Additionally, in each system there was a significant difference in the raw physiologic and operative severity scores between survivors and those who died. A risk-stratification model was applied to each set of data, showing a correlation between an increase in risk and an increase in mortality rate. Finally, the receiver-operator characteristic curves generated showed that in this study group POSSUM, P-POSSUM and Cr-POSSUM were all satisfactory predictive tools although the latter tended to be relatively less accurate. CONCLUSION: Physiologic and operative severity score for the enumeration of mortality and morbidity, P-POSSUM and Cr-POSSUM are all reliable predictors of postoperative mortality in the Australasian context; although there was a trend towards POSSUM and P-POSSUM being better predictors than Cr-POSSUM. However, Cr-POSSUM requires fewer individual patient parameters to be calculated and is thus easier to generate. An ideal preoperative scoring system remains to be developed for predicting mortality in patients undergoing colorectal surgery.

Adolescent↗
PubMed2000

Daytime sleepiness predicts mortality and cardiovascular disease in older adults. The Cardiovascular Health Study Research Group.

INTRODUCTION: As part of the baseline examination in the Cardiovascular Health Study, sleep disturbance symptoms including snoring and daytime sleepiness, were assessed as potential risk factors or precipitants of cardiovascular disease (CVD). Because of the association of sleep disturbance with poorer health and the possible associations of sleep apnea with CVD, we hypothesized that those with poorer sleep or daytime sleepiness may be at increased risk of mortality or incident CVD. SETTING: Participants (n = 5888) were recruited in 1989, with an additional minority cohort recruited in 1993, in four US communities for a cohort study designed to evaluate risk factors for cardiovascular disease. METHODS: An interview-administered questionnaire regarding health and sleep habits with ongoing ascertainment of total mortality and cardiovascular disease morbidity and mortality, including total CVD morbidity and mortality, incident myocardial infarction, and congestive heart failure. RESULTS: Daytime sleepiness was the only sleep symptom that was significantly associated with mortality in both men and women. The unadjusted hazard ratio was 2.12 (1.66, 2.72) in women and 1.40 (1.12, 1.73) in men. Men who reported difficulty falling asleep also had an increased mortality rate (HR = 1.43 (1.14, 1.80)) which was not seen in women. The risks were attenuated with adjustment for age but remained significant for daytime sleepiness in women (HR = 1.82 (1.42, 2.34)) and for difficulty falling asleep in men. (HR = 1.29 (1.03, 1.63)). Frequent awakenings, early morning awakening, and snoring were not associated with a significantly increased risk of mortality in these older men and women. Crude event rates were evaluated for total incident cardiovascular morbidity and mortality, incident myocardial infarction, and incident congestive heart failure (CHF). Incident CVD rates were higher in both men and women with daytime sleepiness. The aged adjusted HR was 1.35 (95% CI = 1.03, 1.76) in men and was 1.66 (95% CI = 1.28, 2.16) in women. Incident CVD was not higher in those with any other sleep disturbance including snoring. The risk of CVD events associated with daytime sleepiness was attenuated but remained significant in women after adjustment for age. Incident myocardial infarction (MI) rates were also higher in women with daytime sleepiness but were not significantly higher in men. Incident CHF rates were increased in both men and women with daytime sleepiness. In men, the age adjusted HR was 1.49 (95% CI, 1.12- 1.98) and in women, was 2.21 (95% CI, 1.64-2.98). Women reporting both daytime sleepiness and frequent awakening had a hazard ratio of 2.34 (95% CI, 1.66-3.29) for incident CHF compared with those with daytime sleepiness but without frequent awakening. This interaction was not found in men. CONCLUSIONS: In this study, daytime sleepiness was the only sleep disturbance symptom that was associated with mortality, incident CVD morbidity and mortality, MI, and CHF. These findings were stronger in women than men, i.e., the associations persisted for mortality, CVD, and CHF in women after adjustment for age and other factors. Thus, a report of daytime sleepiness identifies older adults at increased risk for total and cardiovascular mortality, and is an independent risk factor in women.

Age Factors↗