Observed Death Rate Research Articles

Is there a glycemic threshold for mortality risk?

To determine whether there are thresholds for fasting and for 2-h glucose above which the risk of death from all causes and from coronary heart disease (CHD) increases. We studied 23-year mortality data from the Paris Prospective Study of the 7,018 men, aged 44-55 years, who were not known as diabetic at the baseline examination. The effect of glucose concentrations on mortality was studied using the observed relative risks and an age-adjusted Cox proportional hazards model. For all causes of death, there were J-shaped relationships with both fasting and 2-h glucose concentrations, and the lowest observed death rates were in the intervals centered on 5.5 mmol/l for fasting glucose and 5.0 mmol/l for 2-h glucose. The death rates for CHD were low in this population: for fasting glucose, the hazards ratio was best modeled by a positive linear relationship; for 2-h glucose, it was modeled by a J-shaped curve and the lowest observed death rate was in the interval centered on 6.0 mmol/l. In the Paris Prospective Study, there were no clear thresholds for fasting or 2-h glucose concentrations above which mortality sharply increased; in the upper levels of the glucose distributions, the risk of death progressively increased with increasing fasting and 2-h glucose concentrations.

Estimation of mortality and morbidity risk in vascular surgery using POSSUM and the Portsmouth predictor equation.

The Physiological and Operative Severity Score for enUmeration of Mortality and morbidity (POSSUM) is a simple scoring system previously validated in general surgical patients which enables estimation of the risk of complications and death after operation. The Portsmouth predictor equation (P-POSSUM) is a modification that may result in more accurate prediction of death than POSSUM. The aim of this study was to test the validity of POSSUM and P-POSSUM in patients undergoing major arterial surgery in a specialist unit. Physiological and operative severity scores in 221 patients undergoing elective and emergency arterial surgery in a pure vascular practice under a single consultant were recorded prospectively. Observed morbidity and mortality rates were compared with the rates predicted by POSSUM and P-POSSUM using a linear method of analysis. The POSSUM equation overestimated deaths with this analysis but the mortality rate estimated by P-POSSUM was not significantly different from the observed death rate. The risk of morbidity predicted by POSSUM was not significantly different from the observed complication rate. The POSSUM methodology combined with the P-POSSUM adjustment for death allows satisfactory prediction of mortality and morbidity rates in patients undergoing vascular surgery.

Radiotoxicity of plutonium in NTA-degrading Chelatobacter heintzii cell suspensions.

The radiotoxicity of plutonium in NTA-degrading Chelatobacter heintzii cell suspensions was investigated as part of a more general study to establish the key interactions between actinide-organic complexes and microorganisms in the subsurface. The radiation tolerance of C. heintzii, based on 60Co gamma irradiation experiments, was 165 +/- 30 Gy. No bacteria survived irradiation doses greater than 500 Gy. In the presence of plutonium, where alpha particle decay was the primary source of ionizing radiation, the observed toxicity was predominantly radiolytic rather than chemical. This was evident by the greater effect of activity, rather than concentration, on the toxicity noted. Bioassociation of plutonium with C. heintzii was postulated to be an important and necessary step in the observed loss of cell viability since this was the best way to account for the observed death rate. The radiotoxicity of plutonium towards bacteria is a potentially important consideration in the bioremediation of sites contaminated with radionuclide-organic mixtures and the bioprocessing of nuclear waste.

Analysis of exogenous components of mortality risks.

A new technique for deriving exogenous components of mortality risks from national vital statistics has been developed. Each observed death rate Dij (where i corresponds to calendar time (year or interval of years) and j denotes the number of corresponding age group) was represented as Dij = Aj + BiCj, and unknown quantities Aj, Bi, and Cj were estimated by a special procedure using the least-squares principle. The coefficients of variation do not exceed 10%. It is shown that the term Aj can be interpreted as the endogenous and the second term BiCj as the exogenous components of the death rate. The aggregate of endogenous components Aj can be described by a regression function, corresponding to the Gompertz-Makeham law, A(tau) = gamma + beta x e alpha tau, where gamma, beta, and alpha are constants, tau is age, A(tau) [symbol: see text] tau = tau j identical to A(tau j) identical to Aj and tau j is the value of age tau in jth age group. The coefficients of variation for such a representation does not exceed 4%. An analysis of exogenous risk levels in the Moscow and Russian populations during 1980-1995 shows that since 1992 all components of exogenous risk in the Moscow population had been increasing up to 1994. The greatest contribution to the total level of exogenous risk was lethal diseases, and their death rate was 387 deaths per 100,000 persons in 1994, i.e., 61.9% of all deaths. The dynamics of exogenous mortality risk change during 1990-1994 in the Moscow population and in the Russian population without Moscow had been identical: the risk had been increasing and its value in the Russian population had been higher than that in the Moscow population.

Urban Trauma Transport of Assaulted Patients Using Nonmedical Personnel

To describe one urban trauma transport system to clarify the impact of transport by nonmedical personnel on patient outcome. Retrospective data were assembled over a six-year period through the use of the state trauma registry for an urban county served by seven state-accredited trauma centers. A subset of 4,767 consecutive assaulted patients was analyzed using the TRISS method to estimate survival probability. An unexpected death index (UDI), calculated as the difference between expected (TRISS method) and observed death rates, also was determined. Outcomes for patients transported by fire medics (FMs) vs nonmedical, police personnel (NPs) were compared. FMs transported 2,108 (44%) and NPs transported 1,356 (29%) of the injured assault victims. The FM-transported patients had a lower expected probability of survival than had the NP-transported patients (p < 0.001). This also was true within the penetrating-injury subgroup (p < 0.001), but not the blunt-injury subgroup. The observed death rate was higher for all the FM-transported patients than it was for the NP-transported patients (15% vs 11%; p < 0.01). The UDIs were not different overall, although the NP-transported patients who had blunt trauma had a significantly lower UDI (p < 0.01). NP transport of assaulted patients is generally associated with equivalent outcomes in comparison with FM transport in this urban environment. However, these data also provide evidence of an on-scene implicit triage with more severely injured patients generally transported by FMs.

Excess Mortality in Critically III Patients with Nosocomial Bloodstream Infections

To determine the excess mortality attributable to hospital-acquired bloodstream infections, we applied the acute physiology and chronic health evaluation (APACHE) II classification to 34 critically ill patients with this complication. The study included primary bloodstream infections, defined by a positive blood culture at least three days after hospitalization, in the absence of any other apparent source of infection. The most frequent blood isolates included Staphylococcus aureus (39 percent), Gram-negative rods (24 percent), and Candida albicans (15 percent); the spectrum of blood isolates suggested that most infections were related to intravascular catheters. In a control group of intensive care unit patients (n = 384), the death rate predicted by APACHE II was similar to the observed death rate (35.3 vs 37.8 percent). In a subgroup of control patients (n = 34), chosen for APACHE II scores that matched the patients with bloodstream infections, predicted and observed death rates were also similar (53.1 vs 52.9 percent). For patients with bloodstream infections, however, observed mortality (82.4 percent) significantly exceeded the predicted value (54.1 percent, p = 0.025). We conclude that critically ill patients who develop nosocomial bloodstream infections are at greater risk of death than patients with comparable severity of illness without this complication. The difference between the observed and predicted death rates, 28 percent, represents the excess mortality associated with bloodstream infection in critically ill patients.

Biased Estimates of Expected Acute Myocardial Infarction Mortality Using Medis-Groups Admission Severity Groups

This study examines whether the MedisGroups admission severity groups give unbiased estimates of 30-day mortality in 3037 Medicare-aged patients who were hospitalized in 1985 through 1986 with acute myocardial infarction. The average observed death rate for all acute myocardial infarction patients in the study who were in a given admission severity group was used to estimate the expected death probability for each case in a given group. (This is the same method used by the Pennsylvania Health Care Cost Containment Council for risk adjusting hospital mortality by diagnosis related groups in that state.) When compared with observed deaths, estimates of expected mortality were significantly biased for many patient attributes (eg, age, location of acute myocardial infarction, history of congestive heart failure, serum potassium level, serum urea nitrogen level, pulse rate, and blood pressure). These results are consistent with a conclusion that the MedisGroups scoring algorithm omits some important risk variables, inappropriately includes some other variables reflecting postadmission status, and gives the wrong weights to some appropriate risk variables. To the extent that these findings are also applicable to current MedisGroups scoring algorithms and to other conditions and procedures, MedisGroups admission severity groups cannot fairly adjust for interhospital case mix differences in outcome studies.

Interactive effects of age and other risk factors on long-term survival after coronary artery surgery

The effect of age at the time of coronary artery bypass graft surgery on postoperative survival was studied in 2,507 patients with significant coronary artery disease. Patients were subdivided into five groups based on age at the time of surgery: 20 to 39, 40 to 49, 50 to 59, 60 to 69 and ≥70 years. The observed death rate was compared with that expected for subjects from the general U.S. population matched for age, gender, race and calendar year.For patients ≤59 years of age, the ratio of observed to expected death rates was significantly greater than unity (observed/expected = 4.9 for ages 20 to 39,1.9 for ages 40 to 49 and 1.3 for ages 50 to 59 years, p < 0.01). The prevalence of risk factors, including diabetes mellitus, hypertension, hypercholesterolemia and cigarette smoking, was evaluated in the different age subgroups. When patients were subdivided on the basis of history of cigarette smoking, the decreased relative survival rate of younger (<60 years old) patients existed only in those who smoked observed/expected = 6.0 for ages 20 to 39, 2.2 for ages 40 to 49 and 1.4 for ages 50 to 59 years). In nonsmokers, observed/expected ratios for every age group were not significantly different from unity.Thus, the reduced relative survival rate of younger patients after coronary artery bypass graft surgery may be attributed to the interactive harmful effects of cigarette smoking.

Survival of released pheasants, Phasianus colchicus, in Ireland

The survival of 250 hand‐reared pheasants was assessed by resightings of tagged individuals following their release into an open‐roofed pen on an estate in Ireland. The death rates per 10 days after release were approximated as 5.5% during the first 30 days, 11.6% between 31–70 days, 6.0% between 70–240 days and 2.3% between 241–365 days. The birds suffered their highest rate of loss (48.2%) during their first 10 days after leaving the release pen. This emergence‐related mortality was the major factor influencing changes in the observed death rate following release. Predators, mainly foxes, were initially attracted to the area by the presence of inaccessible prey. Males suffered a higher rate of loss following their emergence from the release pen than did the females, possibly associated with the greater proportion of time thereafter spent outside the pen and hence at risk. The factors affecting the survival of hand‐reared pheasants are discussed. It is suggested that reducing densities of birds within pens may increase subsequent survival without resorting to predator control.

The Iowa record-linkage study. II. Excess mortality among patients with organic mental disorders.

Of 543 patients with organic mental disorders hospitalized at the University of Iowa Psychiatric Hospital, Iowa City, during a ten-year period, 87 died. This mortality was significant based on a control population. Patients of all ages were at risk for early death, especially those younger than 40 years. Risk was greatest during the first two years of follow-up; thereafter the observed death rate approached the expected rate. Patients were at special risk for death from "natural" causes, particularly cancer and heart disease among women, and influenza or pneumonia or "other" natural causes among men. During the first two years of follow-up, men were also at risk for death from accidents or suicide. Women with alcohol- and drug-related psychoses were at risk for death early in follow-up, but the diagnosis was not associated with risk from "unnatural death" in either sex.

Reproduction and Survival of the Desert Tortoise (Scaptochelys agassizii) in Ivanpah Valley, California

Eighty-seven adult desert tortoises (58 females, 29 males) in Ivanpah Valley, California, were fitted with radiotransmitters in 1980 and 1981. All were marked, weighed, and measured and released. Tortoises were then recaptured, weighed and released about every two weeks in 1980 and weekly in 1981. The experiment concluded in the spring of 1982, when 62 tortoises were recovered. Survival of males and females did not differ, but the observed death rate in 1981-82 (18.4%) was significantly greater than that in 1980-81 (4.4%). Females > 200 mm in plastron length exhibited two periods of distinct loss of mass in 1980 (15-28 May, 12-25 June) when masses of males were essentially unchanged. Losses of > 100 g were interpreted as evidence of egg-laying. Eleven of 15 females for which we had season-long records in 1980 laid two clutches, two laid one clutch and two did not lay eggs. The mean number of clutches laid was 1.60. Of 40 females considered in 1981, 20 laid one clutch, 12 laid two clutches and eight did not lay. The mean number of clutches was 1.10. The estimated dry standing crop of forbs in 1980 was about 100 times that in 1981. Estimated biomass of grasses in 1980 was about 25 times that measured in 1981. Analyses of tortoise feces showed that grasses were eaten with equal frequency until mid-May in both years, but that after this time grasses essentially disappeared from 1981 diets. Annuals and seeds were much better represented in early spring diets in 1980 than in 1981. Cacti were more frequent in scats collected in 1981, particularly after mid-May-when about 87% of material in feces was from such plants. Cacti may serve as a reserve supply of energy, but more importantly as a potential source of water. This may partially explain the egg production in 1981-one of the most unfavorable years on record in the Mojave Desert.

A COMPARISON OF INTENSIVE CARE IN THE U.S.A. AND FRANCE

1260 emergency admissions to the intensive-care units (ICUs) of five U.S.A. and seven French tertiary-care hospitals were surveyed by means of a standard severity-of-illness classification system. The 586 patients admitted to French ICUs were significantly younger than the 674 U.S.A. patients, more had been transferred from another hospital, and they remained in the ICU twice as long. Although actual death rates, severity of illness, and the amount of treatment were extremely similar, fewer French than U.S.A. patients were admitted for observation and monitoring. Invasive monitoring was used less in French patients than in U.S.A. patients. The mortality predicted for French patients if they had been treated in the U.S.A. was similar to the observed mortality in the three most frequent indications for ICU admission (cardiovascular, respiratory, and neurological organ-system failure) but was lower than the observed death rate for French gastrointestinal patients. These results suggest that future international studies within separate diagnostic groups would provide insights into the value of many services now commonly used in the treatment of acutely ill patients.

On the Interpretation of Age Distributions

Abstract Given a national census and a life table we may wish to infer the birth rate and hence the rate of natural increase. The model for making the inference here presented specifies the form of the preceding births and an intuitively selected life table if death statistics are not available. A signal on the appropriateness of the model is provided by (a) the resemblance of the age distribution derived from the model to the observed age distribution, and (b) the closeness of the inferred death rate to the observed death rate which has been implicitly fed into the computation; when either of these disparities is too great no result is printed out. Three other ways of obtaining an estimate of births are presented, each with its own characteristic properties. When the four methods agree with one another they can be applied to provide a birth rate in default of birth statistics, or to suggest a correction for birth statistics which are deficient. A table showing results on the four methods for 25 cases enables the reader to judge the practical usefulness of the system.

On the interpretation of age distributions.

Abstract Given a national census and a life table we may wish to infer the birth rate and hence the rate of natural increase. The model for making the inference here presented specifies the form of the preceding births and an intuitively selected life table if death statistics are not available. A signal on the appropriateness of the model is provided by (a) the resemblance of the age distribution derived from the model to the observed age distribution, and (b) the closeness of the inferred death rate to the observed death rate which has been implicitly fed into the computation; when either of these disparities is too great no result is printed out. Three other ways of obtaining an estimate of births are presented, each with its own characteristic properties. When the four methods agree with one another they can be applied to provide a birth rate in default of birth statistics, or to suggest a correction for birth statistics which are deficient. A table showing results on the four methods for 25 cases ena...

LUNG CANCER IN A FLUORSPAR MINING COMMUNITY. I. RADIATION, DUST, AND MORTALITY EXPERIENCE.

Since 1952 two to three deaths from primary cancer of the lung have occurred regularly each year among the male inhabitants of the small fluorspar mining community of St. Lawrence, Newfoundland. These constituted 23 of the 51 deaths that occurred during the 10-year period 1952-61 among employees with one or more years of underground mining experience. A shift to a younger average age at death from lung cancer and an association between age at entry into risk and age at death were observed. Comparisons between the mortality experience of the inhabitants of St. Lawrence, of a control community of comparable size in the same geographical region, and of the population of the rest of Newfoundland confirmed the probability of an occupational factor, the observed death rate from lung cancer being about 29 times the expected. The outstanding environmental finding in the fluorspar mines was the discovery of concentrations of radon and daughter products in the air well in excess of suggested maximum permissible concentrations. On the basis of these concentrations and other considerations, it is suggested that undergound workers were probably exposed to an average potential alpha-energy to complete decay of between 2·5 and 10 times the previously suggested working level of 1·3 × 10⁵ Mev per litre of air (Holaday, Rushing, Coleman, Woolrich, Kusnetz, and Bale, 1957). That these levels were obtained in mines in which no radioactive ore bodies have been found is of exceptional interest. The findings at St. Lawrence are compared with those reported in the literature for uranium mines.