Models to predict prognosis in older patients with heart failure complicated by pre-frailty and frailty: a pilot prospective cohort study.

INTRODUCTION: There are no clinical prediction models to predict the prognosis of pre-frailty or frailty in patients with heart failure. We aimed to develop prediction models for the prognosis of pre-frailty and frailty in older patients with heart failure using the classification and regression tree (CART) method; we then tested the predictive accuracies of the developed models. METHODS: Patients with pre-frailty or frailty at admission were divided into improved and non-improved groups. The CART method was used to establish two models: A, which predicted the presence or absence of pre-frailty improvement during hospitalisation; and B, which predicted the presence or absence of frailty improvement during hospitalisation. RESULTS: Patients with heart failure complicated by pre-frailty (n=28) or frailty (n=156) were included. In model A, the accuracy of predicting pre-frailty improvement was high; the best predictor was single-leg standing time at admission, followed by left ventricular ejection fraction at admission. In model B, the accuracy of predicting frailty improvement was moderate; the best predictor was hand grip strength at admission, followed by estimated glomerular filtration rate at admission, haemoglobin level at admission, and change in single-leg standing time during hospitalisation. The areas under the receiver operating characteristic curves of the CART models were 0.96 and 0.84 in models A and B, respectively. CONCLUSION: Although conditions at admission may predict the improvement of pre-frailty and frailty during hospitalisation, cardiac rehabilitation that improves single-leg standing time may help to improve frailty, particularly when conditions at admission are poor.

An international data analysis on the level of maternal and child health in relation to socioeconomic factors.

International data on health and socioeconomic factors were analyzed to understand the trends and the determinants of maternal and infant mortality in the late years. Multivariate analyses were carried out to summarize the structure of the data. Multiple regression analyses were also carried out with these two mortality rates as dependent variables. The range of independent variables included health resource availability, immunization, GNP, illiteracy rates, distribution in working area, the indicators of living standards such as percentage of telephone lines and television sets per capita and the percentages of working children, population with access to safe water and sanitation, people living in urban areas, among others. In the preliminary analysis the indicators of living standards appeared highly correlated to maternal and infant mortality. Working area (industrial or agricultural) showed also an important correlation. In factor analysis indirect variables (economic and living condition) were summarized into two factors. Two regression analyses were executed. In the first the variables were used directly, while factors obtained by the factor analysis were used in the second. The second analysis confirmed the previous analysis: fertility rate, immunization and urbanization appeared as determinants of maternal mortality. Birth rate, percentage of females working in agriculture and total illiteracy appeared as determinants of infant mortality. The factors extracted in the factor analysis made a significant contribution to the second regression analysis. We concluded: 1) The factors extracted by factor analyses from indirect variables had high explanatory ability on infant mortality rates, 2) The presence of immunization together with birth rate and fertility rate in the regression models pointed out the importance of investing in birth rate reduction and disease prevention methods.

Low power laser protects human erythrocytes In an In vitro model of artificial heart-lung machines.

The protective effect of the low power helium-neon (He-Ne) laser against the damage of human erythrocytes in whole blood was examined in a perfusion model using an artificial heart-lung machine. Preserved human whole blood was diluted and perfused in 2 closed circuits with a double roller pump. The laser irradiated one of the circuits (laser group), and none the other (control group). In the laser group, erythrocyte deformability and erythrocyte adenosine triphosphate (ATP) levels were significantly higher, and free hemoglobin levels were significantly lower than those in the control group. Subsequent morphological findings by means of scanning electron microscope were consistent with these results. Low power He-Ne laser protected human erythrocytes in the preserved diluted whole blood from the damage caused by experimental artificial heart-lung machines. The clinical application of low power laser treatment for extracorporeal circulation is suggested.

A mathematical analysis of the spread of HIV/AIDS in Japan.

The spread of HIV/AIDS in Japan was analysed using a mathematical model incorporating pair formations between adults and sexual contacts with commercial sex workers. The parameters involved in the model were carefully specified as realistically as possible to the actual situation in Japan. Plausible ranges were assigned to those parameters for which values are not known precisely. The model was used to simulate the effect of HIV infected commercial sex workers introduced into a population without HIV. It was shown that the model could generate different scenarios, an explosive infection or a temporal spread, according to different settings of the parameters. Then the condition for occasional introduction of HIV infected commercial sex workers to be able to cause an explosive spread of HIV infection was analysed. This condition was summarized in terms of the critical transmission probability so that we could easily evaluate the degree of the risk. For some unclear parameters, sensitivity to the critical transmission probability was calculated. We also calculated a plausible range of the critical transmission probability using the Latin hypercube sampling method where the parameters were distributed on the plausible ranges. According to the analyses of the model it is concluded that the actual situation of HIV spread in Japan should lie very near the critical point that determines whether the explosive HIV spread actually takes place. This also suggests that effective action taken immediately could be useful to prevent explosive HIV infection in Japan.

The transmission dynamics of antibiotic-resistant bacteria: the relationship between resistance in commensal organisms and antibiotic consumption.

We propose a mathematical model of the transmission dynamics of colonization by commensal bacteria within a human community subject to varying levels of antibiotic use designed to control morbidity induced by pathogenic strains of the normally commensal organisms. Colonization is assumed not to induce morbidity in the majority of cases, and antibiotic use is assumed to be related to the arrival and growth of pathogenic strains that give rise to infections including clinical symptoms of disease. In the absence of antibiotic resistance, the model shows how the pattern of antibiotic prescription and use can eliminate the non-pathogenic commensal strains from the host community if the fraction of people taking antibiotics with a defined efficacy exceeds some critical level. The model is extended to take account of the evolution of antibiotic resistance in the commensal population. We assume resistance may be either plasmid-mediated or conferred by selection of low-level pre-existing mutants, and that resistant organisms may experience reduced reproductive fitness. Invasion of the host community by drug-resistant commensals is possible if certain antibiotic prescribing patterns pertain. We calculate these conditions in terms of the transmission parameter of the organism and the level of antibiotic prescription and use. The model is employed to address the issues of how best to use antibiotics in populations harbouring resistant organisms, and when resistant bacteria will out-compete sensitive strains.

[Analysis of participation rates of atomic bomb survivors in health examinations].

Participation rates of atomic bomb survivors in health examinations were analyzed with a multiple logistic regression model. Rates were obtained for each stratum by sex, age group and residential ward. The effect of residential wards was considered in relation to the social indices of the wards. The effects of sex, age group and residential ward on participation rates were as follows: (1) Females had higher participation rates than males in the working age group (40-64). No sex differences were seen after age 65. (2) The participation rates had a peak around age 70 and were exceptionally high also in the youngest age group (40-44). (3) Participation rates were higher in suburban wards than in central wards. The participation rates had a negative correlation with urban characteristics while they had a positive correlation with suburban characteristics. In particular they had significant negative correlation to the number of clinics and positive correlation with voter participation rates in elections. These results suggest the need for a new type of urban health examination and reflection of the general attitude of the residents to the government.

Bioelectrical impedance measuring method for standing load evaluation.

A bioelectrical impedance method was used to evaluate the workload in standing jobs. This method is designed to indirectly evaluate swelling of the lower leg by measuring the change in the rate of impedance of the lower leg. In this paper, we studied the relationship between the methods used for swelling evaluation, and studied the measuring conditions of the impedance method by using bioelectrical models. Furthermore, impedance in ten male subjects in three types of standing conditions was measured to check the validity of the model analysis. The results are as follows: 1) The result of theoretical analysis showed that the change in impedance caused by leg swelling is equal to the value obtained by the leg volume measuring method, and twice as great as the value obtained by the leg circumference measuring method. The rate of change in impedance at low frequency is about 4 times greater than that at high frequency. The low frequency impedance measuring method is therefore much more sensitive than the other methods. 2) The results of experimental studies showed that the impedance in the lower legs was reduced as the function of time when quietly standing for 30 mins. The change in the rate of impedance was 6.86 +/- 4.54% (mean +/- SD). This rate is 3-5 times greater than the data reported by other researchers who used volume measurement or impedance measurement at high frequency. This difference fits the results of model analysis, and proved the validity of model analysis and the usefulness of the impedance method as an index of the standing load.(ABSTRACT TRUNCATED AT 250 WORDS)

A simple apparatus using inclinometer for monitoring working postures.

A new apparatus was developed for evaluating a load on the low back caused by working postures by measuring upper body inclination. This apparatus consists of an inclinometer and a portable unit. The inclinometer that uses a magnetic resistance sensor is attached to the upper body of the subject. The portable unit, controlled by a one-chip CPU, is enclosed in a cloth case and carried by the subject on his waist belt. The inclination is measured at a certain interval and recorded in the memory of the portable unit. All the recorded data are later transferred to a host computer and then analyzed. According to the theoretical analysis by using a simple mathematical model, upper body inclination changes according to the height of work places, and one cm difference in height causes more than one degree of upper body inclination. A model work of material handling was carried out to collect sample data. Two male subjects lifted ten boxes onto a platform from a stand in several heights. Both stooped and squat lifting methods were used as the lifting protocol. The mean and standard deviation (SD) of the upper body inclination during work decreased according to the lift distance only in stooped lifting. As a practical application, working postures during the task of changing diapers for handicapped people were analyzed with out apparatus. A female subject changed diapers eight times at different height of beds. The mean value of inclination decreased according to the height of the beds.(ABSTRACT TRUNCATED AT 250 WORDS)

Statistical analysis and prediction on incidence of infectious diseases based on trend and seasonality.

We proposed a prediction methodology for the incidence of infectious diseases using incidence data on measles and influenza for forty years in Japan. We also proposed a diagram that makes it possible to convey information on infectious disease incidence more attractively to a wider audience. This can be a useful tool for health promotion in the community. The obtained results are as follows: 1. It was advantageous to use data transformed by logarithm in statistical analysis of infectious disease incidence. 2. The incidences of measles and influenza exhibited strong seasonality. Measles was most frequent in June and influenza in February. 3. Long-term trends were extracted from the derived data obtained by eliminating seasonal effects from the original data. For measles, a decline was accelerated by the introduction of vaccination program in 1978. Influenza also showed a decline for these thirty years. 4. The observed incidence data were quite well predicted by only the trend and the seasonality. The squares of multiple regression coefficients of measles and influenza were 0.84 and 0.58, respectively. The analysis of the residuals suggested there was a possibility of improvement in prediction. 5. The improvement in prediction was attained by incorporating an autoregressive component of the residuals. As a result, the squares of multiple correlation coefficients of measles and influenza increased to 0.97 and to 0.79, respectively. 6. We finally proposed the TS-decomposition diagram to facilitate practical use of incidence data. In this diagram, current incidence data and predicted values for the near future are plotted on the plane where the trend and the seasonality are superimposed.(ABSTRACT TRUNCATED AT 250 WORDS)

[Current and future perspectives of medical information network systems for community health using personal computers and IC cards].

Recent developments in computer and communication technology were studied in relation to medical information network systems, using computers and IC cards, to solve problems in community health. Trial use of personal computer network systems among physicians and IC card systems for personal health data management are already in existence in some parts of Japan. These trials were studied and analyzed based on a questionnaire survey of physicians and patients. Results of the study produced some useful points that should be considered when introducing these systems. These included: 1) details on expectations and specifications for these systems by physicians and patients, 2) easy access to valuable information is a key point for active network systems among physicians, 3) plausibility of improvement of communication between physicians and patients by using these systems, 4) recognition that an important problem concerns patient information privacy and must be considered before introducing these systems. A study of practical merits of these systems and methodology for realization indicates that participation by active and attractive providers of information can be expected to stimulate frequent use of the network system. The cost of introducing these systems can be partially borne by eliminating the large investment now allocated for processing requests for reimbursement of medical services. Investigation into the introduction of medical information systems provides a good opportunity to elucidate problems in the present medical systems.

[Analysis of measuring conditions of surface electromyogram using mathematical model].

To study the measuring conditions of surface electromyogram for work analysis in the field of industrial health, the effect of electrode fixation, electrode distance and electrode-muscle distance were studied using a mathematical model. The results were as follows; 1) The output waveforms of two electrode fixed models, i.e., parallel-fixed model (two electrodes were fixed in parallel to the direction of the muscle fibers) and transverse-fixed model (two electrodes were fixed in transverse to the direction of the muscle fibers) were compared. The maximum output and rectified integrated output of the parallel-fixed model were 2.59 times and 1.2-1.5 times larger than those of transverse-fixed model, respectively. The high output area of the parallel-fixed model was only one round area, but the areas of transverse-fixed model were four round areas which were wider than the area of the parallel-fixed model. The rectified integrated output of the parallel-fixed model was more affected by the location of neuro-muscular junction than that of transverse-fixed model when the electrodes were fixed near the neuro-muscular junction. 2) The rectified integrated output increased by electrode distance, and the changing rate of the rectified integrated output by electrode distance was particularly large when the electrode distance was shorter than 2 cm.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of a system for analyzing working postures.

In order to assist in the analysis of working postures which might cause lumbago in the field of industrial health, a system was developed for the synchronous recording and analyzing of postures, work content and physiological data. The system is composed of a portable unit for recording 3 channels of goniometers, 1 channel of inclinometer and 1 channel of surface electromyogram, a video camera for recording work content, a host computer and some peripheral devices for analyzing the data from the portable unit and video camera. In this system, postures are automatically classified from data on joint angles and upper body inclination angle by using a discriminant function. The joint angles are measured by the goniometers using rubber optical fibers. The angle of upper body inclination is obtained by the inclinometer using a magnetic resistance sensor. In addition to the work content and video images, the postures and the electromyogram can be analyzed and confirmed by simultaneous display of the data on the host computer screen. Based on the trial use of this system in a work model of manual baggage handling, it was proved useful for evaluating in detail the workload caused by working postures.

[Development of posture measuring apparatus using goniometer and inclinometer. 2. Fixation, precision and calibration of goniometer].

A new posture measuring apparatus was developed for time and motion study in the field of industrial health. This apparatus records working postures by measuring angles of joints and trunk inclination. The angles of joints were measured by the newly developed goniometers which use the bending loss of rubber optical fibers. This paper presents results of studies made on the fixation, precision and calibration of goniometers which are important in the actual application of this apparatus. Six freedoms of five joints were examined, i.e. elbow (flexion/extension), shoulder (abduction/adduction and horizontal adduction/abduction), hip (flexion/extension), knee (flexion/extension), ankle (dorsi-flexion/plantar-flexion). The results obtained were as follows; 1) Goniometers should be fixed according to the characteristics of each joint. 2) The output errors were calculated from the measured data, excluding the effects of flexed angles, subjects and fixations. The mean output error of all joints was 0.189 V (14.3 degree). 3) The output errors by the three calibration methods using logistic curves were calculated. The output errors for 2-point method (calibrated by the data of minimum and maximum angles) and 3-point method (calibrated by the data of minimum, medium and maximum angles) were 1.34 and 1.22 times larger than the output errors (0.139 V) for all-point method (calibrated by all measured data), respectively.

Clinical analysis of reexpansion pulmonary edema.

Twenty-one of 146 cases of spontaneous pneumothorax that were treated by thoracentesis or continuous low negative pressure suction drainage (-12 cm H2O) of the pleural space developed REPE. The rate of REPE was higher in patients 20 to 39 years of age than in those over the age of 40, and the rate progressively increased in proportion to the extent of pneumothorax, as assessed by roentgenographic criteria. It is postulated that age-related changes in the lung may afford some degree of protection against developing REPE. It is also suggested that the treatment of pneumothorax with thoracentesis and/or suction drainage in young patients, or in the face of a large pneumothorax, requires careful consideration in view of a relatively high incidence of REPE in such individuals.

[Survey of attitudes among general practitioners regarding the introduction of a personal computer medical network system in community health care].

General practitioners (GPs) play an important part in community health care. Their opinion regarding introduction of a medical information network system using a personal computer and factors influencing the decision to introduce such a system were surveyed among 977 randomly sampled GPs. A response from 727 GPs was obtained. Based on a two stage selection method, 20 factors were selected as effective factors among the 73 factors surveyed, with the following results: (1) Responses to the question concerning the approval of system introduction were classified into three groups: "not necessary + too early to make a decision (DA)" (DA group), "approve (A)" (A group) and "undecided (UD)" (UD group). Each group had nearly equal numbers of respondees. (2) Significant effective factors were "experience with personal computers", "a desire to use a personal computer", "a desire to use a computer-diagnosis-system", "cost", and "a volition to operate a computer by himself". (3) The "A group" had high experience and affirmative opinions, while the "DA group" had low experience and negative opinions. The "UD group" also tended to respond with "do not know" regarding the factors. (4) Approval of system introduction requires providing basic knowledge on computers, opportunities for positive experience with computers, and practical examples of problem solutions in a general practitioner's work.

[An analysis of the effect of measles vaccination program by a mathematical model].

The reported case rates of measles during 1967-1986 were analyzed and compared with rates predicted by a mathematical model for measles prevalence. In Japan, measles vaccination was introduced in October, 1978. Since data before and after the introduction were available, the effect of the vaccination program could be analyzed. The mathematical model was constructed by modifying the Kermack-McKendrick model. In the model, environmental virus density was involved as an additional variable and the 'death' (inactivation) rate of the virus was assumed to show seasonal variation. The strategy for prevention and eradication was also discussed. The main results were as follows: 1. The characteristics of measles prevalence were (1) seasonal (annual) variation which has a peak in May or June and a bottom in September or October, (2) bienniality (before the vaccination), i.e., higher prevalence and lower prevalence years alternate every other year, and (3) trienniality (after the vaccination), i.e., a higher prevalence year appears every three years. 2. The model could reproduce all these characteristics for a range of probable parameters. 3. According to the model, trienniality was a transient phase and the system finally reached a stationary state that showed neither bienniality nor trienniality. 4. The critical density of the susceptible population necessary for the survivability of the virus in the population, was also obtainable from the model.

[Influence of cardiopulmonary bypass on plasma lipid peroxides].

In 22 patients who underwent cardiac surgery with cardiopulmonary bypass (CPB), we studied the influence of CPB on the level of lipid peroxides (LPO) in plasma by means of measuring the time course of plasma LPO level during and after CPB. We expressed LPO level, which was measured by thiobarbituric acid reaction, as the level of malondialdehyde. In our preliminary study, it was found necessary to correct the plasma LPO level diluted by priming fluids of CPB machine and the concentration of plasma protein was fitted for its correction. In the following study, we used the plasma LPO level corrected by the concentration of plasma protein. LPO were significantly decreased since the initiation of CPB (1.669 +/- 0.208 versus pre-CPB 1.785 +/- 0.158 log nmol MDA/gm protein, p less than 0.05) to the post CPB 30 minutes, except around 60 minutes after initiation of CPB (1.735 +/- 0.242 log nmol MDA/gm protein, p greater than 0.05). As the initial change (the values at 30 minutes after CPB initiation) may express the effect of CPB directly in this time course of LPO, we analyzed the initial change on different background factors. By ordinary analysis of the initial change, as to the effect of type of disease (congenital and acquired), LPO were decreased in the acquired group (1.617 +/- 0.197 versus pre-CPB 1.779 +/- 0.163 log nmol MDA/gm protein, p less than 0.05). At that time the acquired group was significantly different from the congenital group (1.799 +/- 0.191 versus pre-CPB 1.800 +/- 0.157 log nmol MDA/gm protein, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)