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PubMed2001

Effect of trends on detrended fluctuation analysis.

Detrended fluctuation analysis (DFA) is a scaling analysis method used to estimate long-range power-law correlation exponents in noisy signals. Many noisy signals in real systems display trends, so that the scaling results obtained from the DFA method become difficult to analyze. We systematically study the effects of three types of trends--linear, periodic, and power-law trends, and offer examples where these trends are likely to occur in real data. We compare the difference between the scaling results for artificially generated correlated noise and correlated noise with a trend, and study how trends lead to the appearance of crossovers in the scaling behavior. We find that crossovers result from the competition between the scaling of the noise and the "apparent" scaling of the trend. We study how the characteristics of these crossovers depend on (i) the slope of the linear trend; (ii) the amplitude and period of the periodic trend; (iii) the amplitude and power of the power-law trend, and (iv) the length as well as the correlation properties of the noise. Surprisingly, we find that the crossovers in the scaling of noisy signals with trends also follow scaling laws--i.e., long-range power-law dependence of the position of the crossover on the parameters of the trends. We show that the DFA result of noise with a trend can be exactly determined by the superposition of the separate results of the DFA on the noise and on the trend, assuming that the noise and the trend are not correlated. If this superposition rule is not followed, this is an indication that the noise and the superposed trend are not independent, so that removing the trend could lead to changes in the correlation properties of the noise. In addition, we show how to use DFA appropriately to minimize the effects of trends, how to recognize if a crossover indicates indeed a transition from one type to a different type of underlying correlation, or if the crossover is due to a trend without any transition in the dynamical properties of the noise.

Analysis of Variance↗

PubMed1994

Heart disease, cancer, and stroke mortality trends and their interrelations. An international perspective.

BACKGROUND: Changes in mortality from heart disease, cancer, and stroke over recent decades in many countries have received much attention. However, comprehensive and concurrent analyses of these trends and their effect on total mortality have been lacking. Moreover, the extent to which the trends for one disease may relate to those for another disease is unknown. Concordance of trends for major diseases would suggest that they have common causes and thus may be responsive to the same preventive measures. METHODS AND RESULTS: Age-adjusted death rates for total mortality and mortality from heart disease, stroke, lung cancer, and cancer other than lung cancer were obtained for the years 1950 to 1987 in 27 countries by sex and ages 35 to 74 years from the World Health Organization statistical reports. Concordance of mortality trends was assessed for ages 35 to 74 between 1950 and 1983 through visual inspection and semiquantitative measurements of percentage change over time. The epidemic increase in heart disease mortality ended in the 1960s or 1970s in most industrialized countries; death rates often declined very steeply. Stroke mortality also changed from an increase to a decline or from a modest to a steep decline in the 1960s or 1970s. Lung cancer mortality slopes generally changed from a steep increase to either a modest increase, a flat trend, or a decline; the changes in slope are lagging behind those for heart disease and stroke. These improvements influenced trends for total mortality. Cancer other than lung cancer trends are less distinct than those for the three other causes of mortality. Yet, testing them for concordance with heart disease trends reveals that they are mostly concordant on a time-lag analysis that assumes that heart disease responds more rapidly to a change in lifestyle or environment than cancer. Trends for heart disease and lung cancer in men also tend to be concordant on time-lag analysis. Heart disease and stroke trends have become more concordant with time. CONCLUSIONS: Trends for mortality from heart disease, stroke, lung cancer, and, less distinctly, cancer other than lung cancer, tend to be similar in different countries, leading to a corresponding similarity in total mortality trends. An analysis of trends for pairs of diseases within countries indicates a tendency toward concordance of trends, suggesting the existence of common causes amenable to the same preventive measures. This analysis of international mortality trends is intended to stimulate further research along these lines, as a guide to preventive and therapeutic action.

Adult↗

PubMed2006

Flow-specific trends in river-water quality resulting from the effects of the Clean Air Act in three mesoscale, forested river basins in the northeastern United States through 2002.

Two new methods for assessing temporal trends in stream-solute concentrations at specific streamflow ranges were applied to long (40 to 50-year) but sparse (bi-weekly to quarterly sampling) stream-water quality data collected at three forested mesoscale basins along an atmospheric deposition gradient in the northeastern United States (one in north-central Pennsylvania, one in southeastern New York, and one in eastern Maine). The three data sets span the period since the implementation of the Clean Air Act in 1970 and its subsequent amendments. Declining sulfate (O4(2-)) trends since the mid 1960s were identified for all 3 rivers by one or more of the 4 methods of trend detection used. Flow-specific trends were assessed by segmenting the data sets into 3-year and 6-year blocks, then determining concentration-discharge relationships for each block. Declining sulfate (O4(2-)) trends at median flow were similar to trends determined using a Seasonal Kendall Tau test and Sen slope estimator. The trend of declining O4(2-) concentrations differed at high, median and low flow since the mid 1980s at YWC and NR, and at high and low flow at WR, but the trends leveled or reversed at high flow from 1999 through 2002. Trends for the period of record at high flows were similar to medium- and low-flow trends for Ca2++ Mg2+ concentrations at WR, non-significant at YWC, and were more negative at low flow than at high flow at NR; trends in nitrate (NO3-), and alkalinity (ALK) concentrations were different at different flow conditions, and in ways that are consistent with the hydrology and deposition history at each watershed. Quarterly sampling is adequate for assessing average-flow trends in the chemical parameters assessed over long time periods (approximately decades). However, with even a modest effort at sampling a range of flow conditions within each year, trends at specified flows for constituents with strong concentration-discharge relationships can be evaluated and may allow early detection of ecosystem response to climate change and pollution management strategies.

Acid Rain↗

PubMed2003

Why are lung cancer rate trends so different in the United States and United kingdom?

Over the period 1951-1995, lung cancer rates in men aged 35-74 yr more than doubled in the United States but declined slightly in the United Kingdom. In women, rates rose about sevenfold in the United States but only about threefold in the United Kingdom. To investigate whether these very different trends in lung cancer risk could be explained by smoking habits, trends in smoking were compared in the two countries and a multistage model was used to predict lung cancer rates from detailed data on age of starting and stopping smoking, amount smoked per smoker, and sales-weighted average tar levels. In both countries, there was a similar switch to filter cigarettes, reduction in tar levels and the average age of starting to smoke, and decline in prevalence of smoking in women aged under 50 yr and in men. Although some differences were evident, most notably in older women where prevalence of smoking and consumption per adult has increased more in the United States, these trends do not appear to explain the markedly different trends in lung cancer, evident in both sexes and all age groups. The multistage analyses confirmed these tentative conclusions-the differing trends in smoking in the two countries could not explain the markedly differing trends in lung cancer. Lung cancer trends in the United Kingdom were found to be clearly more favorable than expected on the basis of smoking trends, while trends in the United States were less favorable. In sensitivity analyses, these conclusions were found not to be materially dependent on the precise methods used, including whether tar reduction was or was not assumed to be beneficial. The explanation for these findings must lie in changes over time, differing in the two countries, in aspects of smoking not considered in these analyses and/or in exposure to other risk factors. Evidence relating to a number of possible such smoking variables (including type of tobacco, curing, use of pesticides and additives, and butt length) or other risk factors (including air pollution, radon, asbestos, obesity, and marijuana) is discussed, but no clear explanation of the findings is offered. Further research is urgently needed to investigate the causes of these apparently anomalous trends in lung cancer and in smoking habits. Criticism is also presented of the views recently expressed by the authors of NCI Monograph 13 that tar reduction has been ineffective in lowering lung cancer risk and that trends in lung cancer in the United States fit in well with trends in smoking habits.

Adult↗

PubMed1993

Trends in cancer incidence and mortality.

Time trends in cancer risk have often been summarised by the observation that mortality from cancers associated with tobacco is increasing rapidly, while mortality from all other cancers is either stable or falling slightly, this slight decline being dominated by the decrease in mortality from stomach cancer. Until recently, and with some variation between the sexes, this simple summary of cancer mortality trends would have been broadly correct for a number of developed countries, and it remains useful in dismissing claims of an impending and unexplained epidemic of cancer, but it does not apply to all countries, and in some there have recently been striking changes in the trends in mortality from cancers associated with tobacco. Cancer mortality has been widely accepted as the most important measure of progress against cancer, since it reflects the impact of cancer on people, and has been considered less subject to distortion than incidence or survival, although this is open to question. Cancer mortality also reflects trends in incidence and survival to a greater or lesser extent. There has been controversy, however, over how cancer mortality trends should be interpreted, as well as over which measures should be used to assess progress in cancer control. An overall summary of trends in mortality from all cancers combined is of limited value in assessing progress against cancer, in any case. Increases in a common lethal cancer may numerically dominate overall mortality trends, perhaps concealing declines in less common or less lethal cancers, while opposite trends in cancers of the lung and stomach, for example, might lead to an overall impression that little has changed. Further, up to a third of cancer patients will not die of cancer, and cancer mortality statistics do not reflect their experience at all. Cancer mortality trends only indirectly reflect trends in the number of people who are diagnosed with cancer in a given year, and those who do die of cancer in a given year may have been diagnosed more than 3 years previously, even though many die earlier: this blurs the responsiveness of routine cancer mortality statistics as a measure of recent progress, and alternative measures have been proposed. Trends in competing risks of death, especially at higher ages, may also complicate the interpretation of cancer mortality trends. The chance of developing cancer, and in that event, the chances of surviving it, are of direct interest to individuals.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed1996

Managing temporal worlds for medical trend diagnosis.

The medical trend diagnosis system TrenDx has been applied as a prototype for diagnosing pediatric growth disorders, and as a proof of concept in detecting clinically significant trends in hemodynamics and blood gases in intensive care unit patients. TrenDx diagnoses trends by matching patient data to patterns of normal and abnormal trends called trend templates that define disorders as typical patterns of relevant variables. These patterns consist of a partially ordered set of temporal intervals with uncertain endpoints. Bound to each temporal interval are value constraints on real-valued functions of measurable parameters. The temporal uncertainty in trend templates allows TrenDx to conclude both what trend pattern best matches the data and also when significant landmarks and phase transitions have occurred within the best matching trend. The temporal uncertainty in trend templates requires that TrenDx consider alternate temporal worlds in monitoring patient data. The number of temporal worlds grows worst case polynomially in the number of time slices of data. To manage the competing temporal worlds, TrenDx employs two techniques: beam search based on regression scores, and temporal granularity in the trend template definitions. These two techniques, described here in detail, allow TrenDx to choose different points in the trade-off between accuracy of trend detection and algorithm efficiency.

Algorithms↗

PubMed1998

Automated electrocardiograph ST segment trending monitors: accuracy in detecting myocardial ischemia.

UNLABELLED: Continuous automated ST segment trending devices (ST trending monitors) are included in most new operating room electrocardiography (ECG) monitors to facilitate ischemia detection, but their efficacy is not well validated. Therefore, we compared their accuracy with that of Holter ECG recorders in detecting ST segment changes (both analyzed offline) in 94 patients undergoing coronary artery bypass graft surgery. Holter ECG tapes were analyzed using standard criteria for determining ECG ischemic episodes, which were compared with those measured by the ST trending monitors. Overall, 42 ischemic episodes were detected by using the Holter monitor in 30 patients. Of the 42 episodes, 38 (90%) were also detected by the ST trending monitors. Sixteen episodes of ST segment deviation were detected by the ST trending monitors, but not by the Holter. The sensitivity of the three ST trending monitors in detecting ischemia was 75%, 78%, and 60% for the Marquette (Milwaukee, WI), Hewlett Packard (Andover, MA), and Datex (Helsinki, Finland) monitors, respectively, with a specificity of 89%, 71%, and 69% relative to the Holter. Compared with the HP and Datex monitors, the Marquette monitor has the best agreement with the Holter (K 0.64). Conditions in which ST trending monitors may be inaccurate were identified and included the appearance of small R-wave amplitude, drifting baseline, and during periods of conduction abnormalities and pacing. We conclude that ST trending monitors have only moderate sensitivity and specificity (< 75% overall) in accurately detecting ECG ST segment changes compared with Holter ECG recordings. Therefore, sole reliance on ST trending monitors for the detection of myocardial ischemia may be insufficient. IMPLICATIONS: Using Holter recordings as the reference standard for detection of intraoperative ischemia, ST trending monitors were found to have overall sensitivity and specificity of 74% and 73%, respectively. Several conditions contribute to the inaccuracy of ST trend monitoring, and additional modification of their performance is necessary to achieve better agreement with the Holter analysis.

Aged↗

PubMed1995

Ischaemic heart disease: trends in mortality in Hong Kong, 1970-89.

STUDY OBJECTIVE: To describe the time trends for ischaemic heart disease (IHD) mortality in Hong Kong between 1970 and 1989, and to examine these trends in relation to the risk factors for IHD. DESIGN: A descriptive epidemiological study of time trends using mortality and population data from the Hong Kong Census and Statistics Department. Direct standardisation using the world population was made to adjust for the changing age structure. Log-linear analyses for trends were performed for the whole period and separately for 1970-79 and 1980-89. The cohort effect was studied by regrouping the data into five year groups according to the year of birth. The influences of risk factors, including hypertension, diet, and smoking, on the time trends of IHD were explored. The role of improved hospital treatment of myocardial infarction on the trends of mortality from categories of IHD was also examined. SETTING: The total Hong Kong population, 1970-89. MAIN RESULTS: The substantial and steady decline of IHD mortality seen in most western countries in the past two decades was not observed in Hong Kong, which showed a plateau or slowly decreasing trend only in the past decade for both women and men. The decreasing trends were more apparent in the younger age groups, especially for women. Cohort analysis showed no significant cohort effect in men, but women born more recently had a lower mortality. Trends of risk factors did not show any close relationship with the mortality trends of IHD, except that a decrease in cigarette smoking might have contributed to the slight decrease in IHD mortality in recent years. Better detection and wider availability of treatment for hypertension might also have contributed to the decrease in IHD mortality. CONCLUSIONS: Hong Kong started to show a slow decline in IHD mortality during the 1980s, about one to two decades later than in other western countries and with the decreasing trend less pronounced. The reasons for this decline are not clear. More detailed information from systematic, population based surveys on life style and risk factors for IHD among the general population are needed.

Adult↗

PubMed1990

Research on secular trends in auxology.

Current status of research on secular trends in growth and maturation is considered from several perspectives. The need to define secular trends as positive, negative or absent is initially discussed. Positive secular trends, i.e., increases in size and earlier maturation, characterize the majority of the auxological literature. However, some populations have experienced negative secular trends or no trends. Positive secular trends and cessation of secular trends in stature and age at menarche are described for developed countries, followed by a brief discussion of secular changes in body proportions and composition. Data from developing countries illustrate all three types of secular trends. Some segments of the population show positive changes in size and age at menarche, while others show no evidence of secular change or negative secular trends. Finally, comparisons of estimated statures in earlier European populations suggest a negative secular trend, i.e., a decline in estimated stature from about the 11th to the 19th centuries, which is followed by a positive secular trend starting about the mid-19th century.

Adolescent↗

PubMed1990

Test of socioeconomic causation of secular trend: stature changes among favored and oppressed South Africans are parallel.

Secular trends in body height, however common, run at different rates and even in opposite directions in various populations. The standard explanation is that direction and tempo of the trend are reflections of changes in the socioeconomic situation. The aim of this work is to test this hypothesis by examining trends in different socioeconomic groups living in the same country. Our observations on affluent South Africans of European extraction (AE) and on Polish medical students are compared with the data on statures of other affluent and poor peoples from the two countries measured at various dates during the 19th and 20th centuries. The trend among native Southern Africans is erratic (Tobias: South African Journal of Medical Science 40:145-164, 1975), but the overall direction is positive with a slow rate (0.24 cm/decade for 72 Negroid male groups and 0.48 cm/d for 28 Khoisan male samples). Magnitude of the trend among adult AE (0.41 cm/d for females, 0.59 for males) does not differ significantly from that among natives. The trend was absent in the data for 10-year-old AE boys and girls. The rate of trend among AE is much lower than that in their countries of origin (mainly Holland and Britain). The trend among AE medical students is markedly weaker than the trend among Polish medical students (1.21 cm/d), who in turn parallel Polish general conscripts (1.24 cm/d). It follows that the explanation of the secular trend as being an ecosensitive response of individuals to changing levels of well-being is insufficient.

Adult↗

PubMed1992

Implications of birth cohort patterns in interpreting trends in breast cancer rates.

BACKGROUND: Most investigations of trends in cancer rates are based on a cross-sectional approach, i.e., an examination of trends in rates by year of diagnosis or death. When there are longitudinal effects (i.e., trends in rates with successive birth cohorts), interpretation of cross-sectional trends can be misleading. Based on cross-sectional comparisons, U.S. breast cancer mortality rates have been reported to be decreasing over the last 20 years in younger women but to be increasing during the same period in older women. PURPOSE: To examine the impact of longitudinal effects on the divergence of cross-sectional trends in breast cancer mortality with age, we examined breast cancer mortality rates from 1969 to 1988 by birth cohort for White women in the United States. METHODS: By using a novel, nonparametric, permutational method to analyze 2-year, age-specific mortality rates for women aged 30-89 years, we identified trends in rates with successive birth cohorts. RESULTS: The divergence in trends with age is shown to be consistent with an increase in breast cancer risk with successive birth cohorts from 1900 to 1916 and with a decrease in breast cancer risk with successive birth cohorts beginning around 1926. CONCLUSION: Longitudinal effects have a significant impact on cross-sectional trends in breast cancer mortality. IMPLICATIONS: Continuation of the birth cohort trend in younger women, which could correspond to changes in reproductive patterns accompanying the "baby boom," would result in decreasing cross-sectional trends in women 60-69 years of age over the next decade and in women 70-79 years of age in the subsequent decade. Longitudinal effects must be taken into consideration when monitoring and evaluating the effects of early detection, treatment, and intervention programs using national rates.

Adult↗

PubMed2006

Changing patterns in breast cancer incidence trends.

Incidence rates for breast cancer in U.S. women have steadily increased for decades, but the reasons are not well understood. A recent upturn in these trends suggests that one component may be the effect of more aggressive screening in the population. The age-period-cohort framework, in which the temporal components associated with year of diagnosis and generation are evaluated, can assist in interpreting the elements associated with these trends. A unique approach for exploring other ways of partitioning the contribution of the different temporal components is described and applied to breast cancer incidence data (ICDO 174.0-174.9) from the Surveillance, Epidemiology and End Results (SEER) registries. Single-year intervals for age and year of diagnosis were used to fit models that provide estimates of the trends associated with the individual temporal elements. A log-linear model for age, period, and cohort was fitted using Poisson regression, and estimates of the separate time trends were calculated. The trends with period increased after 1982, when more aggressive screening began, and the trend is steeper for women older than 40 years. Cohort trends have increased steadily, although recent cohorts appear to be somewhat flat for women aged 50 years or younger, whereas the trend for those older than 50 years have continued to increase. Estimates of cohort trends in rates are also provided by extrapolating what would have occurred had there been no period trend before or after 1982, thus providing an estimate of the magnitude of the upturn that occurred after the recent emphasis on screening.

Adult↗

PubMed1990

Growth, body weight, survival, and tumor trends in (C57BL/6 X C3H/HeN) F1 (B6C3F1) mice during a nine-year period.

Time trends for growth, body weight, survival and tumor prevalences in 121 diet control groups with a total of 4,636 male B6C3F1 mice and 123 diet control groups with a total of 4,758 female mice of NCI-NTP 2-yr chemical carcinogenicity studies started during a 9-yr period (1973 to 1981) in 11 laboratories were evaluated. Male and female mice did not show substantial changes in growth patterns. Both sexes had highly significant time trends with decreasing body weights in the more recent studies. This apparent trend was due to high body weights during the first 3 yr and highly significant interlaboratory variability. Time trends for survival of both sexes were not significant. Prevalences of liver tumors, lung tumors, and lymphoma in males and lung tumors in females did not show significant time trends. There were significant positive time trends for prevalences of liver tumors and lymphoma in female mice, but the trends were not significant when adjusted for interlaboratory variability. The positive time trend for anterior pituitary tumors of females was highly significant and may be due in part to an increase in the amount of pituitary tissue examined in the more recent studies. Histological reevaluation of liver and anterior pituitary tissue in 208-249 female mice at each of 4 different times periods did not substantially change the prevalences or the time trends. The major factor influencing time trends in mice appeared to be interlaboratory variability.

Animals↗

PubMed2002

Age trends in the level of serum testosterone and other hormones in middle-aged men: longitudinal results from the Massachusetts male aging study.

We used longitudinal data from the Massachusetts Male Aging Study, a large population-based random-sample cohort of men aged 40-70 yr at baseline, to establish normative age trends for serum level of T and related hormones in middle-aged men and to test whether general health status affected the age trends. Of 1,709 men enrolled in 1987-1989, 1,156 were followed up 7-10 yr afterward. By repeated-measures statistical analysis, we estimated simultaneously the cross-sectional age trend of each hormone between subjects within the baseline data, the cross-sectional trend between subjects within the follow-up data, and the longitudinal trend within subjects between baseline and follow-up. Total T declined cross-sectionally at 0.8%/yr of age within the follow-up data, whereas both free and albumin-bound T declined at about 2%/yr, all significantly more steeply than within the baseline data. Sex hormone-binding globulin increased cross-sectionally at 1.6%/yr in the follow-up data, similarly to baseline. The longitudinal decline within subjects between baseline and follow-up was considerably steeper than the cross-sectional trend within measurement times for total T (1.6%/yr) and bioavailable T (2-3%/yr). Dehydroepiandrosterone, dehydroepiandrosterone sulfate, cortisol, and estrone showed significant longitudinal declines, whereas dihydrotestosterone, pituitary gonadotropins, and PRL rose longitudinally. Apparent good health, defined as absence of chronic illness, prescription medication, obesity, or excessive drinking, added 10-15% to the level of several androgens and attenuated the cross-sectional trends in T and LH but did not otherwise affect longitudinal or cross-sectional trends. The paradoxical finding that longitudinal age trends were steeper than cross-sectional trends suggests that incident poor health may accelerate the age-related decline in androgen levels.

Adult↗

PubMed1999

Genetic trends and breed overlap derived from multiple-breed genetic evaluations of beef cattle for growth traits.

Genetic evaluations for a multiple-breed population of beef cattle were used to estimate genetic trends for five breeds, and genetic differences and overlap among 14 breeds. Genetic evaluations studied were for direct contributions to birth weight, gain from birth to 200 and 365 d, and maternal contribution to gain from birth to 200 d. Almost all genetic trends were positive, but the magnitude of the trends varied among breeds. Trends were nonlinear between 1985 and 1995 for most breed and trait combinations. The rates of increase in genetic trends were generally higher for the lighter weight breeds, and lighter weight breeds had faster growth rate genetic trends at 1995 than the heavier breeds. Genetic trend estimates for yearling gain at 1995 were 2.46, 2.23, 1.73, 1.70, and 1.46 kg/yr for Angus, Hereford, Limousin, Charolais, and Simmental, respectively. Corresponding birth weight genetic trends were .130, .226, .049, .130, and .048 kg/yr. Mean genetic differences between breeds have been decreasing in magnitude due to these differences in genetic trends between heavier and lighter breeds. Genetic variation for the traits studied seemed to be greater within than between breeds for calves born and cows calving between 1993 and 1995. Genetic trends at 1995 suggest that ratios of within:between breed variation will increase and that across-breed genetic improvement initiatives for growth traits will become more important in the future.

Animals↗

PubMed1999

[The trend in pregnancies terminated by a cesarean operation in Mexico during 1991-1995].

In the last decades has been a worldwide trend to increase the number of cesarean sections as an alternative of obstetric resolution, phenomenon for which it was proposed a variety of explanation, this fact remains practically unknown in the institutions of the National Health System (NHS) in Mexico. To identify the trend of the pregnancy to end for cesarean sections during the years of 1991-1995 in the 32 states of de country, as well as of all the institutions of the National Health System. Descriptive, cross sectional and retrospective. We use the data of the Bureau of Statistics and Informatics of de Health Ministry of each one of the 32 states of the country, of the years 1991 to 1995, and of the number of cesarean sections made in the hospitals of the different institutions of the NHS. We started off with a data-base, to calculate frequency tables, and the specific rate of the cesarean section for each year, for each one of the states and institutions of the NHS. We calculate the secular trends using the annual rates of cesarean section, for each one of the states and institutions of the NHS. We also made bivariate analysis and estimated the odds ratio (OR) and 95% Confidence Interval (95% IC); and the statistic X2 for trend, setting the two tailed statistic significance level of 0.05. During the study period, there was 7,503,817 births in all hospitals of the NHS, of these births 1,929,865 (25.72%) was resolved by cesarean section. For the whole period it there was a clear trend to increment of the cesarean section, the rate for 1991 was 20.44%, and by 1995 was 28.58%, the raise for the period was 39.82%, with values of the OR for trend of 1.56; 95% IC (1.55-1.57). "P" < 0.05. The rate for institutions attending open population had an increment of 35.08% [OR trend 1.45; 95% IC (1.43-1.46), "p" < 0.05], of them the highest rate was for the State System of Health in 1995 with 29.78%, the rates for the remaining institutions varied from 16.57% for the IMSS/SOLIDARIDAD and 21.7% for the Health Ministry, all trends were statistically significant. In relation to the institutes attending closed population the raise was of 53.27% [OR trend 1.82; 95% IC (1.81-1.83), "p" < 0.05], with the highest rate for the National Defense Ministry which had a rate of 51-15%, the rates for the remaining institutions varied from 33.52% for the Mexican Institute of Social Security (IMSS) to 43.89% for the Institute of Safety and Social Services for the State Workers (ISSSTE), with exception of the Management of the Medical Services of the Mexican Oils (PEMEX) and the Marine Ministry (SECMAR), all trends were statistically significant. When the analysis of the cesarean section rates for the 32 states of the Mexican Republic was carried out, we found that in 1995, the national average rate was 28.58%, the lowest rate corresponded to the state of Zacatecas with 19.82% and the highest to the state of Nuevo León with 42.14%. There was a tendency to increment for all states which varied from 23.55% for the state Chiapas and 67.97% for the states of Querétaro, all increments were statistically significant. We conclude, that rates of cesarean section for both, institutions of NHS and states of the Mexican Republic, are of the highest in the world, no matter what big the interinstitutional and interstate variation are. The highest rates occurred in institutions attending closed population, and the states with a higher degree of socioeconomic development.

Cesarean Section↗

PubMed1997

Trends in leprosy case detection rates.

BACKGROUND: A systematic review of the trends in leprosy incidence is lacking. The question of whether leprosy transmission has declined remains, therefore, unanswered. This study investigates trends in new case detection rates (NCDRs) in selected leprosy-endemic areas from different continents. METHODS: A literature search using specific inclusion criteria was performed. Average annual rates of change in NCDRs were obtained by exponential curve fitting. The variation in trends within individual areas was investigated using direct and indirect information on leprosy control activities. RESULTS: This review covers 16 areas in the Pacific, Asia, Africa and Latin America. For 10 out of the 16 areas, the trend was seen to be declining consistently over the last 10 years or longer. Near stabilization or stabilization after decline was observed for two areas. For three areas, interpretation of recent NCDRs was difficult due to changes in control, but two of them showed a decline over the study period. A consistently increasing trend was observed over the last 20 years in the one remaining area. The observed downward trends could not be attributed to reduced control activities or changed diagnostic criteria. A general acceleration of downward trends in the NCDR after the introduction of multidrug therapy (MDT) has not so far occurred. CONCLUSION: Our main conclusion is that despite many differences between the studies and study areas, the review demonstrates a considerable tendency of downward NCDR trends. Lack of information and changing control conditions necessitate caution in interpreting NCDR trends in individual areas. A general impact of MDT on NCDR trends is so far not visible. The coming years will be crucial for MDT-based control to prove its ability to reduce leprosy incidence.

Adult↗

PubMed1996

Worldwide trends in cancer mortality in the elderly, 1955-1992.

Trends in age-standardised mortality for all cancers and 21 cancers or groups of cancers over the period 1955-1992 were analysed for 33 countries from four continents in a population aged 65-84 years. Mortality from all neoplasms in the elderly showed heterogeneous patterns in various countries and in the two sexes. Trends were generally more favourable for females than for males, reflecting essentially the earlier and more extensive impact of the lung cancer (and other tobacco-related neoplasms) epidemic in elderly males, in addition to the earlier decline of gastric cancer and a widespread decline of cervical cancer rates in females. In several countries, particularly from western Europe, but also Japan, cancer mortality trends were more favourable over the last two decades than in earlier calendar periods. Some countries of northern and central Europe (including Finland, Germany, Austria and Switzerland) showed stable or even downward trends over time for total cancer mortality in both sexes, particularly in males. This reflects the different patterns of the tobacco-related (lung) cancer epidemic in various countries, and the impact of a few other major neoplasms, including in particular the systematic downward trends in stomach cancer. In contrast, rates were moderately upwards in males in North America, and several countries of southern and eastern Europe, where cancer mortality in the elderly was comparatively low in the 1950s, showed appreciable upward trends, mostly in males. Thus, there was a generalised tendency towards a levelling of the differences in certified cancer mortality in the elderly population in various areas of the world. Although there are substantial limits and uncertainties in the reliability and validity of cancer death certification and their trends in the elderly, there is no widespread and generalised upward trend in cancer mortality, with a major exception of lung and other tobacco-related neoplasms. Furthermore, in several countries, cancer mortality trends over the last four decades have been favourable for elderly women.

Aged↗