The perinatal morbidity and mortality survey of Jamaica 1986–1987

Summary. The Jamaican Perinatal Morbidity and Mortality Survey was conducted between September 1986 and August 1987. A total of 10310 consecutive births were identified and mothers interviewed in the first 2 months (main cohort study), 1405 neonatal admissions were evaluated over a 6-month period (morbidity study), and 1855 perinatal deaths and 73 late neonatal deaths identified over 12 months (mortality study)-55% of the deaths were given a postmortem examination. The perinatal mortality rate for the cohort study was 38.1 per 1000 births. This was 36.6 percent higher than the 1982 estimate of 27.9/1000 based on deliveries at the Victoria Jubilee Hospital, a specialist maternity institution which has at least 13 000 deliveries per annum.     

Perinatal deaths as a result of immaturity in Jamaica

Summary. During the 12-month period from 1 September 1986 to 31 August 1987 an attempt was made to collect information on all perinatal deaths occurring on the island of Jamaica. Of the 2069 late fetal and early neonatal deaths identified, 19% fell into the Wigglesworth¹ definition of 'deaths from immaturity'. Twins were 11 times more likely to die of immaturity than were singletons, and twins comprised 18% of all deaths in this group.
Comparison of the singleton deaths from immaturity, with 9919 singletons born on the island during the 2-month period of September and October 1987 and who survived the first 7 days, revealed several strong risk factors. These included history of previous miscarriages, stillbirth, early neonatal death or preterm delivery, and complications of bleeding and hypertension (highest diastolic, proteinuria and eclampsia all having independent associations). None of these factors 'explained' a strong negative relationship with the number of young children in the household. There was an apparent protective effect of maternal folic acid ingestion which warrants further investigation.     

Perinatal mortality survey in Jamaica: aims and methodology

Summary. The Jamaican Perinatal Mortality Survey was designed to identify the true perinatal mortality rate, and assess the factors which could contribute towards a reduction in perinatal mortality on the island.
All births in a 2-month period ( n = 10527) were compared with all perinatal deaths occurring over a 12-month period ( n = 2069). Over half the deaths ( n = 1058) received a detailed post-mortem examination.
Use of the Wigglesworth classification identifies the major component of perinatal death in this country to be associated with intrapartum asphyxia (44% of deaths). Deaths due to congenital malformations and miscellaneous causes contribute relatively little (< 10%) to the overall mortality rate. Over a quarter of deaths apparently occur before the onset of labour, and a fifth are prematurely liveborn but die of causes related to immaturity.     

Antenatal and perinatal care in Jamaica: do they reduce perinatal death rates?

Summary. Information concerning 9919 singleton pregnancies delivered in Jamaica in the 2-month period of September and October 1986 and surviving the early neonatal period were compared with 1847 singleton perinatal deaths occurring in the 12-month period from 1 September 1986 to 31 August 1987, classified according to the Wigglesworth schema.
Logistic regression was used to assess features of antenatal and intrapartum care that were associated with the different groups of perinatal death after taking account of environmental, maternal and medical factors.
In Jamaica, 67% of all mothers took iron during pregnancy. These mothers appeared to have a lower risk of perinatal death. This does not appear to be an artefact related to the gestation at which the mother delivers, and was particularly associated with antepartum fetal deaths.
Commencement of antenatal care in the first trimester appeared to reduce the risk of all perinatal deaths, and for intrapartum asphyxia in particular. It is speculated that the mechanism may involve early detection and treatment of anaemia and syphilis.
Quality of perinatal care available in the area of residence, as measured by the presence of consultant obstetricians and a paediatric consultant unit, is shown to be significantly related to a reduction in deaths from intrapartum asphyxia, but it appeared not to be related to antepartum fetal deaths.     

Deaths associated with intrapartum asphyxia in Jamaica

Summary. The Jamaican Perinatal Mortality Survey compared all 2069 perinatal deaths occurring during the 12 months between 1 September 1986 and 31 August 1987 with 10086 survivors born in the 2 months of September and October 1986. The Wigglesworth classification identified 44% of the deaths as attributable to intrapartum asphyxia (IPA), and this grouping was largely confirmed by post-mortem examination where it had been carried out. About half of these babies weighed 2500 g + and death should have been largely preventable.
Comparison of the 813 IPA singleton deaths with 9919 singleton survivors using logistic regression showed independent associations with maternal employment status, the number of children in the household, maternal height, whether or not the mother was trying to get pregnant, or had ever used an intrauterine contraceptive device. Medical conditions such as syphilis, untreated vaginal infection, bleeding < 28 weeks, bleeding 28+ weeks, highest diastolic and first diastolic blood pressures and eclamptic fits antenatally were all strongly associated. Mothers who commenced antenatal care in the first trimester were at reduced risk as were those who took iron during pregnancy. There were substantial reductions in mortality in areas where better medical facilities were available.
To this model, features of previous obstetric history were offered, but the only variables which entered were those relating to prior perinatal deaths and immediately preceding miscarriage and termination.
Examination of specific features in the management of labour and delivery is a logical basis for the introduction of changes in practice. Caesarean section is unlikely to be appropriate but it is suggested that more active interventions in terms of use of forceps and/or vacuum extraction may be useful.     

Does maternal behaviour influence the risk of perinatal death in Jamaica?

Summary. Features of behaviour of mothers of singleton perinatal deaths collected over the 12-month period from 1 September 1986 to 31 August 1987 were compared with 9919 mothers of singleton infants born in September and October 1986 and surviving the first week of life, as part of the Jamaican Perinatal Mortality Survey.
For perinatal deaths as a whole, and in the presence of maternal age and social and environmental features, logistic regression analyses showed that the following were independently related with higher risk of mortality: (1) deliberately trying to get pregnant; (2) ever having used Depo Provera; (3) not drinking alcohol in pregnancy; and (4) smoking cigarettes in pregnancy. There were no associations with coital frequency, ever using the contraceptive pill or smoking ganja (cannabis).
Deaths were classified using the Wigglesworth scheme, and separate analyses carried out for the three major groups - antepartum fetal deaths, deaths from immaturity and deaths from intrapartum asphyxia. Antepartum fetal deaths were at increased risk if (1) mothers were deliberately trying to get pregnant or (2) they had ever used Depo Provera. Deaths from immaturity were not associated with any health behaviour variables. Deaths from intrapartum asphyxia were more likely if (1) the mother was deliberately trying to get pregnant or (2) she had never used an intrauterine contraceptive device.     

Twinning rates and survival of twins in rural Nepal

BACKGROUND: Twin pregnancies are common but there are few data on rates of twinning or survival of liveborn twin infants in developing countries. METHODS: The rates of multiple births were calculated in a population-based cohort of married women of childbearing age who were enrolled in a randomized community trial to assess the impact of vitamin A or beta-carotene on maternal and infant health and survival. RESULTS: The rate of twinning was 16.1 per 1000 pregnancies (7.4 if only twin pregnancies resulting in two liveborn infants were used). The rate for triplets and quadruplets was 0.19 and 0.06 per 1000 pregnancies. Twinning rates were higher among women of higher parity, but were not associated with maternal age. Twinning rates among twins where at least one was live born (or increased in utero survival) were 30% (95% CI : -1%, 71%) and 44% (95% CI : 9%, 89%) higher among women receiving vitamin A and beta-carotene supplements than placebo, after adjusting for maternal age, gestational age, and parity. The perinatal mortality rate was 8.54 times higher for twins than singletons, 7.32 higher for neonatal mortality, and 5.84 higher for cumulative 24-week mortality. This difference was reduced but not erased by adjusting for gestational age. No difference in survival of liveborn twin infants was seen by supplement group. A higher mortality rate among male twins was largely explained by gestational age. CONCLUSIONS: Multiple births are relatively common occurrences in rural Nepal, and carry a much higher mortality risk for the infants than for singletons. Vitamin A or beta-carotene supplementation appeared to increase the rate of twinning, or improve the survival of twins in utero, but did not increase twin survival after birth.     

Perinatal mortality in single and multiple births in Japan, 1980–1991

Summary. Perinatal mortality rates (PMR) decreased significantly per year in single, twin, triplet, quadruplet and quintuplet births during the period 1980–1991. The PMRs were 7.7 per 1000 livebirths for singletons, 45.6 for twins, 89.0 for triplets, 116.8 for quadruplets, and 476.2 for quintuplets during the 12 years. The relative risks of perinatal death in multiplets vs. singletons were 6 for twins, 12 for triplets, 15 for quadruplets and 62 for quintuplets. The PMR was significantly higher in males than females for singletons and twins, but there was no sex differential in PMRs for higher order of multiple births. The PMR increased with birth order in twins and triplets, whereas there was no birth order effect on the PMR for quadruplets. An increasing proportion of multiple births among perinatal deaths may be related to the increasing multiple birth rate in Japan.     

A study of mortality among 14,730 male workers in 12 Norwegian ferroalloy plants: cohort characteristics and the main causes of death.

OBJECTIVES: Concern about the health hazards of exposure to workers in the ferroalloy industry has initiated this historical cohort study. The aim was to examine the mortality pattern among male employees in 12 Norwegian ferroalloy plants. METHODS: All men employed for at least six months who started their first employment during 1933-91 were eligible for the cohort. Deaths observed during 1962-90 were compared with expected figures calculated from national mortalities. Internal comparisons of rates were performed by Poisson regression analysis. The final cohort comprised 14,730 male employees who were observed for 288,886 person-years. RESULTS: Mortality from all causes of death was slightly increased (3390 deaths, standardised mortality ratio (SMR) 1.08, 95% confidence interval (95% CI) 1.04-1.11). Regression analysis of total mortality showed a significant negative trend for the rate ratios with increasing duration of employment. An increased mortality was found among employees in urban plants compared with employees in rural plants (rate ratio (RR) 1.21, 95% CI 1.13-1.29). Excess deaths from cancer (SMR 1.11) and sudden death (SMR 1.47) were found among employees with at least three years of employment. Mortality from accidents, poisonings, and violence was increased among all employees (SMR 1.28). Excess deaths from this cause were however only found for the time after the end of employment in this industry and not during employment (SMR 0.90). CONCLUSIONS: The increased mortality from cancer and sudden death could be related to work exposures, at least in subgroups, and these results warrant further studies. The excess deaths from accidents, poisonings, and violence were probably not related to work exposures. The mortality results for short term workers and other information indicate that systematic errors contribute to the increased overall mortality.     

Mortality in the UK industrial silica sand industry: 2. A retrospective cohort study

Aims: To evaluate the mortality experience of a cohort of employees in the UK silica sand industry exposed to respirable crystalline silica (RCS).

Methods: A retrospective cohort mortality study followed all workers to 2001 with at least one year's employment at one of seven UK silica sand producing quarries between 1950 and 1986. Each worker was assigned a job category and cumulative exposure to RCS was estimated using a job-exposure matrix.

Results: A total of 764 deaths were identified in 2703 cohort members. The overall mortality rate for the cohort was lower than would be expected in the general population. Mortality from circulatory and respiratory disease was also less than expected, but death due to pneumoconiosis was slightly raised (two deaths). Mortality from all cancers was slightly decreased. Mortality was not raised in any job category. Cancer mortality was raised at one quarry due to a significant increase in lung (standardised mortality rate (SMR) 162.0, 95% CI 113.5 to 224.3) and bladder (SMR 366.5, 95% CI 167.6 to 695.7) cancers. Mortality from lung cancer and other causes did not show a trend with cumulative exposure to RCS.

Conclusions: This study did not show any consistent relation between RCS exposure (in the absence of other known carcinogens) and the development of lung cancer. This contrasts with a number of studies that have shown positive findings in similar and related industries.

     

Ectopic pregnancy surveillance, United States, 1970-1987

In 1987, both the rate of hospitalizations due to ectopic pregnancy and the number of women hospitalized increased from those reported in 1986. Although ectopic pregnancy represented 1.7% of all pregnancies in 1987, complications of this condition accounted for 12% of all maternal deaths in that year. The case-fatality rate was 3.4 deaths per 10,000 ectopic pregnancies, a decline of 30% from the rate of 4.9 deaths reported in 1986, and a 90% decline from the 35.5 deaths per 10,000 ectopic pregnancies reported in 1970. Although the racial gap decreased slightly in 1987, the risk of ectopic pregnancy remained 1.4 times higher for women of black and other minority races than for white women. The risk of death from this condition remained 1.8 times higher for women of black and other minority races.     

Regression models for clustered binary responses: implications of ignoring the intracluster correlation in an analysis of perinatal mortality in twin gestations

PURPOSE: Dependent binary responses, such as health outcomes in twin pairs or siblings, frequently arise in perinatal epidemiologic research. This gives rise to correlated data, which must be taken into account during analysis to avoid erroneous statistical and biological inferences. METHODS: An analysis of perinatal mortality (fetal deaths plus deaths within the first 28 days) in twins in relation to cluster-varying (those that are unique to each fetus within a twin pregnancy such as birthweight) and cluster-constant (those that are identical for both twins within a sibship such as maternal smoking status) risk factors is presented. Marginal (ordinary logistic regression [OLR] and logistic regression using generalized estimating equations [GEE]) and cluster-specific (conditional and random-intercept logistic regression models) regression models are fit and their results contrasted. The United States "matched multiple data" file of twin births (1995-1997), which includes 285,226 twins from 142,613 pregnancies, was used to examine the implications of ignoring of clustering on regression inferences. RESULTS: The OLR models provide variance estimates for cluster constant covariates that ranged from 7% to 71% smaller than those from GEE-based models. This underestimation is even more pronounced for some cluster-varying covariates, ranging from 21% to 198%. CONCLUSIONS: Ignoring the cluster dependency is likely to affect the precision of covariate effects and consequently interpretation of results. With widespread availability of appropriate software, statistical methods for taking the intracluster dependency into account are easily implemented and necessary.     

Mortality of cellulose fiber production workers

Mortality was studied among 1271 employees of a cellulose fiber production plant in Rock Hill, South Carolina, in the United States. Each subject was employed for at least three months between 1 January 1954 and 1 January 1977 in jobs that entailed exposure to the highest concentrations of methylene chloride. In the cohort 122 deaths were identified through 1 September 1986, and mortality rates for the cohort were compared with mortality rates for York County, South Carolina. Deficit mortality was observed for cancers of the respiratory system, breast, and pancreas and from ischemic heart disease. Excess mortality was observed for cancers of the buccal cavity and pharynx and the liver and biliary tract, and for melanoma as well. The largest relative excess was for liver and biliary tract cancers. There were only four deaths in this category; however, three of the four deaths were cancer of the biliary tract (3 observed, 0.15 expected, standardized mortality ratio 20).     

Birthweight and perinatal mortality among singletons and twins in north-eastern Tanzania

BACKGROUND: Low birthweights as well as high perinatal mortality rates are common in most African populations. Little is known, however, about how low birthweight corresponds with higher mortality rates within African populations. Twins are known to have lower birthweights and higher perinatal mortality rates than singletons. If lower birthweights represent higher perinatal risk per se, small twins within a population with generally lower birthweights should have critically increased risks. METHODS: In total, 15,255 births in a Tanzanian hospital during 1999-2006 were analysed to determine birthweight distribution and examine perinatal mortality rates (including stillbirths and neonatal deaths within 24 hours) by birthweight in twins and singletons. Referral births from outside the district where the hospital was situated were excluded from analysis. RESULTS: The mean birthweight for births within an estimated normal distribution was 3172 g, with a standard deviation of 462 g. The overall perinatal mortality rate was 43.9 per 1000 births (95% confidence interval: 40.7-47.2). Perinatal mortality rates among twins and singletons were 91.0 and 41.1 per 1000 babies respectively, corresponding to a relative risk of 2.2 (95% confidence interval: 1.7-2.8). The birthweight distribution for twins was shifted to lower birthweights. Twins had a generally lower birthweight and an excess of extremely small births as compared to singletons. The increased mortality rate for twins appeared to be independent of birthweight. CONCLUSIONS: The two-fold increased risk of perinatal death for twins was observed across the whole birthweight distribution, and very small twins appeared to have an excess perinatal risk that was almost similar to that of larger twins.     

Impact of the Jamaican birth cohort study on maternal, child and adolescent health policy and practice

McCaw‐Binns A, Ashley D, Samms‐Vaughan M. Impact of the Jamaican birth cohort study on maternal, child and adolescent health policy and practice. Paediatric and Perinatal Epidemiology 2010; 24: 3–11. The Jamaica Perinatal Morbidity and Mortality Survey (JPMMS) was a national study designed to identify modifiable risk factors associated with poor maternal and perinatal outcome. Needing to better understand factors that promote or retard child development, behaviour and academic achievement, we conducted follow‐up studies of the birth cohort. The paper describes the policy developments from the JPMMS and two follow‐up rounds. The initial study (1986–87) documented 94% of all births and their outcomes on the island over 2 months (n = 10 508), and perinatal (n = 2175) and maternal deaths (n = 62) for a further 10 months. A subset of the birth cohort, identified by their date of birth through school records, was seen at ages 11–12 (n = 1715) and 15–16 years (n = 1563). Findings from the initial survey led to, inter alia, clinic‐based screening for syphilis, referral high‐risk clinics run by visiting obstetricians, and the redesign and construction of new labour wards at referral hospitals. The follow‐up studies documented inadequate academic achievement among boys and children attending public schools, and associations between under‐ and over‐nutrition, excessive television viewing (>20 h/week), inadequate parental supervision and behavioural problems. These contributed to the development of a television programming code for children, a National Parenting Policy, policies aimed at improving inter‐sectoral services to children from birth to 5 years (Early Childhood Commission) and behavioural interventions of the Violence Prevention Alliance (an inter‐sectoral NGO) and the Healthy Lifestyles project (Ministry of Health). Indigenous maternal and child health research provided a local evidence base that informed public policy. Collaboration, good communication, being vigilant to opportunities to influence policy, and patience has contributed to our success.     

Ectopic pregnancy in the United States, 1970-1986

In 1986, both the rate of hospitalizations due to ectopic pregnancy and the number of hospitalizations decreased from those reported in the previous year, although the decreases were not statistically significant. If this leveling off of previous yearly increases becomes a continuing trend, possible explanatory hypotheses include a leveling off of disease occurrence, and an increasing use of outpatient management. The case-fatality rate rose slightly in 1986, to 4.9 deaths per 10,000 ectopic pregnancies, although this rate still represents an 86% decline from the 35.5 deaths per 10,000 ectopic pregnancies reported in 1970. In 1986, ectopic pregnancy accounted for only 1.4% of all pregnancies but was associated with over 13% of maternal deaths. Compared with white women, women of black and other minority races had a 1.6 times greater risk of ectopic pregnancy. Ectopic pregnancy remains one of the leading causes of maternal death in the United States and continues to be an important public health problem.     

Causes of stillbirths and early neonatal deaths: data from 7993 pregnancies in six developing countries

OBJECTIVE: To report stillbirth and early neonatal mortality and to quantify the relative importance of different primary obstetric causes of perinatal mortality in 171 perinatal deaths from 7993 pregnancies that ended after 28 weeks in nulliparous women. METHODS: A review of all stillbirths and early newborn deaths reported in the WHO calcium supplementation trial for the prevention of pre-eclampsia conducted at seven WHO collaborating centres in Argentina, Egypt, India, Peru, South Africa and Viet Nam. We used the Baird-Pattinson system to assign primary obstetric causes of death and classified causes of early neonatal death using the International classification of diseases and related health problems, Tenth revision (ICD-10). FINDINGS: Stillbirth rate was 12.5 per 1000 births and early neonatal mortality rate was 9.0 per 1000 live births. Spontaneous preterm delivery and hypertensive disorders were the most common obstetric events leading to perinatal deaths (28.7% and 23.6%, respectively). Prematurity was the main cause of early neonatal deaths (62%). CONCLUSIONS: Advancements in the care of premature infants and prevention of spontaneous preterm labour and hypertensive disorders of pregnancy could lead to a substantial decrease in perinatal mortality in hospital settings in developing countries.     

Prospective community-based cluster census and case-control study of stillbirths and neonatal deaths in the West Bank and Gaza Strip

Obstetric complications and newborn illnesses amenable to basic medical interventions underlie most perinatal deaths. Yet, despite good access to maternal and newborn care in many transitional countries, perinatal mortality is often not monitored in these settings. The present study identified risk factors for perinatal death and the level and causes of stillbirths and neonatal deaths in the West Bank and Gaza Strip. Baseline and follow-up censuses with prospective monitoring of pregnant women and newborns from September 2001 to August 2002 were conducted in 83 randomly selected clusters of 300 households each. A total of 113 of 116 married women 15-49 years old with a stillbirth or neonatal death and 813 randomly selected women with a surviving neonate were interviewed, and obstetric and newborn care records of women with a stillbirth or neonatal death were abstracted. The perinatal and neonatal mortality rates, respectively, were 21.2 [95% confidence interval (CI) 16.5, 25.9] and 14.7 [95% CI 10.2, 19.2] per 1000 livebirths. The most common cause (27%) of 96 perinatal deaths was asphyxia alone (21) or with neonatal sepsis (5), while 18/49 (37%) early and 9/19 (47%) late neonatal deaths were from respiratory distress syndrome (12) or sepsis (9) alone or together (6). Constraint in care seeking, mainly by an Israeli checkpoint, occurred in 8% and 10%, respectively, of 112 pregnancies and labours and 31% of 16 neonates prior to perinatal or late neonatal death. Poor quality care for a complication associated with the death was identified among 40% and 20%, respectively, of 112 pregnancies and labour/deliveries and 43% of 68 neonates. (Correction added after online publication 5 June 2008: The denominators 112 pregnancies, labours, and labour/deliveries, and 16 and 68 neonates were included; and 9% of labours was corrected to 10%.) Risk factors for perinatal death as assessed by multivariable logistic regression included preterm delivery (odds ratio [OR] = 11.9, [95% CI 6.7, 21.2]), antepartum haemorrhage (OR = 5.6, [95% CI 1.5, 20.9]), any severe pregnancy complication (OR = 3.4, [95% CI 1.8, 6.6]), term delivery in a government hospital and having a labour and delivery complication (OR = 3.8, [95% CI 1.2, 12.0]), more than one delivery complication (OR = 4.4, [95% CI 1.8, 10.5]), mother's age >35 years (OR = 2.9, [95% CI 1.3, 6.8]) and primiparity in a full-term pregnancy (OR = 2.6, [1.1, 6.3]). Stillbirths are not officially reportable in the West Bank and Gaza Strip and this is the first time that perinatal mortality has been examined. Interventions to lower stillbirths and neonatal deaths should focus on improving the quality of medical care for important obstetric complications and newborn illnesses. Other transitional countries can draw lessons for their health care systems from these findings.     

Seasonal patterns in perinatal mortality and preterm delivery

An investigation of possible seasonal patterns in preterm delivery and perinatal mortality utilized linked birth, infant death, and fetal death records from Minnesota for the years 1967-1973. Data included over 400,000 white singleton live births and stillbirths of 29 or more weeks completed gestation. Composite monthly cohorts of ongoing pregnancies were constructed for each month of the year and the probability of a preterm delivery and/or perinatal death was estimated. A statistically significant increase in the probability of a preterm delivery or perinatal death occurred during July, August, and September. The probability of a preterm delivery ranged from a low of 55 per 1000 pregnancies at risk in April to a high of over 59 per 1000 in July and August. In addition, although each assigned cause of death group showed a similar pattern, perinatal deaths due to infection in the mother or fetus showed a standardized mortality ratio of 65 in May and 155 in August and September, while the ratios of all other causes combined ranged from 94 to 108. Fetal deaths reported as having occurred before labor began showed a seasonal pattern nearly identical with that for all perinatal deaths, while those occurring during labor showed no seasonal pattern. The findings are consistent with published evidence that environmental factors likely involving ascending infections may play a larger role in preterm delivery and perinatal mortality than has been generally recognized.     

Trends in infant mortality in Barcelona [Spain], 1983-1998

OBJECTIVE: To analyze trends in infant mortality, taking into account its main components and the principal causes of death between 1983 and 1998 in the city of Barcelona (Spain). METHODS: We calculated overall mortality rates and mortality rates by sex for infant, postneonatal, neonatal, early neonatal, and late neonatal mortality in residents of the city of Barcelona from 1983 to 1998. Data were obtained from the births and deaths register. Data were grouped in 4-year periods. Poisson regression models were adjusted to obtain relative risks of mortality for comparison among the 4-year periods. The percentage of variation between rates in the different periods was also calculated. RESULTS: There were 1.564 deaths in the 16 years. 896 (57.3%) were males and 668 (42.7%) were females. Infant mortality rates varied from 10.5 per 1,000 live births in 1986 to 3.4 ten years later (1996). Between 1983 and 1988 mortality rates remained stable, decreasing after 1989. The neonatal mortality rate, and especially the early neonatal mortality rate, showed a greater decrease than the postneonatal mortality rate. The main causes of death were congenital defects (47.4%) and perinatal causes (32.1%). CONCLUSIONS: Mortality rates decreased over the study period but not with the same intensity as in previous deca des.