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At least 19 recordsLinked to original sources
PubMed1975

An improved life table method.

A life table estimates probabilities of surviving and of dying as well as death rates, as these would apply in a stationary population with the same underlying continuous mortality curve as the observed population. We have derived approximations to the probability of surviving that require no iteration, do not depend on graduation or interpolation, and appear to give as precise results as interpolated or iterated tables. On the side of theroy we show that methods due to T.N.E. Greville and to Reed and Merrell are special cases of our formula (3). The new approach is extended to cause-deleted tables and to multiple decrement.

Humans↗
PubMed1987

Long-term treatment of rheumatoid arthritis with sulphasalazine, gold, or penicillamine: a comparison using life-table methods.

Life-table analysis was applied to the records of 317 patients with rheumatoid arthritis (RA) treated with sulphasalazine (SAS), 201 treated with sodium aurothiomalate (gold), and 163 with penicillamine. They comprised all those treated in our department with these drugs between January 1973 and July 1984. Risks of treatment termination for all reasons were similar for each drug at five years (gold 92%, penicillamine 83%, SAS 81%). The risk of treatment termination due to inefficacy was less for gold (29.5%) than for penicillamine (38.1%) or sulphasalazine (41.2%). Adverse effects, however, led to withdrawal of gold in 57%, penicillamine in 41.2%, and SAS in 37%; the most effective drugs appeared most toxic. Serious adverse effects were much more common in association with gold (17.4%) and penicillamine (12.3%) than with SAS (1.6%). Sulphasalazine appears as well tolerated over long periods in RA as gold or penicillamine and is associated with fewer serious adverse effects; of these drugs, it might therefore be considered the agent of first choice.

Actuarial Analysis↗
PubMedDate not supplied

Life-table methods for contraceptive research.

Life-table methods used for the analysis and interpretation of contraceptive follow-up studies differ from those used in other areas of medical research. The historical development of these methods in the contraceptive literature is outlined and the two main methods are discussed, compared and shown to differ mainly in their nomenclature; their results are very similar in practice. The daily life-table method is simpler to apply and interpret, and facilitates analysis using the logrank statistic as well as powerful regression modelling techniques for survival data.

Actuarial Analysis↗
PubMed1987

Dental restoration longevity: a critique of the life table method of analysis.

The use of the life table method for assessing the longevity of dental restorations is growing. One reason for this is the availability of statistical computer packages which can be used by the non-expert, and this is tending to lead to an uncritical approach to the methodology. Although much can be learnt regarding the durability of restorations by using life table analysis, there are many inherent problems related to its use in dental studies. The survival pattern of many restorations is such that long-term studies are required to obtain valid assessments of durability. Results reported after only a few years of study contain many restorations not followed to failure. The ways in which data on these restorations are handled can greatly affect the estimates of longevity. These considerations have not, to date, received sufficient attention.

Actuarial Analysis↗
PubMed1989

Life table method for analyzing relationship between smoking and hypertension.

The life table method is introduced for describing the relationship of smoking amount to prevalence rate of hypertension. The smoking level at different sex groups are collected and grouped according to their cumulative smoking amount. Using the total number of peasants, and the number of hypertensives in each group, one is able to calculate the probability of occurrence of hypertension for each dose group as well as for each cumulative dose group, which indicated that there was a dose-effect curve in estimating the relationship between the cumulative smoking and the probability of hypertension, and females presented a significantly higher probability of hypertension than males in same smoking level.

Adult↗
PubMed1994

[Analysis of therapeutic prognosis of primary open-angle glaucoma by the proportional hazards model and the life-table method].

We retrospectively analyzed the therapeutic prognosis of primary open-angle glaucoma by the life-table method and the proportional hazards model. One hundred and eight patients (202 eyes) were studied. The follow-up period ranged from 6 to 125 months (40 +/- 25 months: mean +/- SD). The Kaplan-Meier life-table method indicated that therapeutic prognosis was significantly related to pretreatment intraocular pressure (IOP) and visual field defect, and that more intensive treatment was needed for higher IOP and more deteriorated visual field defect. Analysis by the proportional hazards model showed that pretreatment IOP and mean deviation (MD) measured by static perimetry were significant prognostic factors for non-surgical treatment and that the hazard ratios were 1.29-1.31 for a 5 mmHg rise in IOP and 1.44-1.83 for a 10 dB fall in MD. We concluded that the therapeutic prognosis of primary open-angle glaucoma is highly related to the level of IOP and the severity of visual field defect at the time of diagnosis.

Adult↗
PubMed1978

Use of the life table method in determining attrition from treatment.

Life table analysis of attendance at an outpatient clinic indicates levels of attrition similar to those reported by follow-up and other studies of treatment for drug dependence. With appropriate qualifications, rates of attrition may be viewed as measures of treatment outcome.

Actuarial Analysis↗
PubMed1989

Life table methods applied to use of medical care and of prescription drugs in early childhood.

Life table methods were applied to analyses of longitudinal data on the use of medical care during the first 5 years of life among all 1701 children born in a Swedish semirural municipality. Cumulative proportions of the children who had used particular types of medical care or prescription drugs at least once by certain ages were estimated. By the fifth birthday, 98% had made at least one visit to any physician and 82% at least one visit to a paediatrician. By the fifth birthday at least one prescription for antibiotics had been purchased at a pharmacy by 82%; and 33% had been admitted to inpatient hospital care at least once (excluding immediate postnatal care). Acute conditions and more chronic diseases were also studied using these methods. At least one visit to a physician at a primary health care centre had been made for acute otitis media in 65% of 5 year olds and for atopic dermatitis in 8%.

Child Health Services↗
PubMed1980

[Comparison between surgical and conservative treatment (106Ru/106Rh beta rays) of choroidal melanoma calculated by survival rate and survival time using the life table method (author's transl)].

According to the literature about 40 to 50 percent of patients with malignant melanoma of the choroid die of metastases within five years of enucleation. These figures justify the search for more effective methods and treatment. Computation of the survival rate using the life table method commonly applied in demographic studies is explained, and described by reference to the practical example of a comparison of two patient collectives. Out of 214 patients treated by enucleation, 67.6% were still alive five years later, while 90.7% of 136 patients treated with 106Ru/106Rh applicators survived the same period of time.

Choroid Neoplasms↗
PubMed1996

Cost effectiveness of lowering cholesterol concentration with statins in patients with and without pre-existing coronary heart disease: life table method applied to health authority population.

OBJECTIVES: To estimate the cost effectiveness of statins in lowering serum cholesterol concentration in people at varying risk of fatal cardiovascular disease and to explore the implications of changing the criteria for intervention on cost and cost effectiveness for a purchasing authority. DESIGN: A life table method was used to model the effect of treatment with a statin on survival over 10 years in men and women aged 45-64. The costs of intervention were estimated from the direct costs of treatment, offset by savings associated with a reduction in coronary angiographies, non-fatal myocardial infarctions, and revascularisation procedures. The robustness of the model to various assumptions was tested in a sensitivity analysis. SETTING: Population of a typical district health authority. MAIN OUTCOME MEASURE: Cost per life year saved. RESULTS: The average cost effectiveness of treating men aged 45-64 with no history of coronary heart disease and a cholesterol concentration > 6.5 mmol/l for 10 years with a statin was 136,000 pounds per life year saved. The average cost effectiveness for patients with pre-existing coronary heart disease and a cholesterol concentration > 5.4 mmol/l was 32,000 pounds. These averages hide enormous differences in cost effectiveness between groups at different risk, ranging from 6000 pounds per life year in men aged 55-64 who have had a myocardial infarction and whose cholesterol concentration is above 7.2 mmol/l to 361,000 pounds per life year saved in women aged 45-54 with angina and a cholesterol concentration of 5.5-6.0 mmol/l. CONCLUSIONS: Lowering serum cholesterol concentration in patients with and without preexisting coronary heart disease is effective and safe, but treatment for all those in whom treatment is likely to be effective is not sustainable within current NHS resources. Data on cost effectiveness data should be taken into account when assessing who should be eligible for treatment.

Age Distribution↗
PubMed1990

[Cumulative incidence rate of divorces for birth cohort estimated by the life-table method].

The trend of divorces has been usually evaluated by the divorce rate. However, it is difficult to make detailed analyses of the trend of or relevant factors concerning divorces by the divorce rate, because the denominator of this index is not a population at risk of divorces. The application of the life-table method to calculation of cumulative incidence rate of divorces for a birth cohort based on vital statistics data was introduced and its problems were discussed. This method was able to give a precise incidence rate of divorces and made it possible to examine the relationship of marital durations, generation of cohorts or age at marriage to the incidence of divorces. The results obtained were as follows: 1. The cumulative incidence rate of divorces increased and the marital duration-specific incidence rate of divorces decreased with continuation of marriages. 2. The cumulative incidence rate of divorces was higher in younger birth cohorts than in older cohorts. 3. The cumulative incidence rate of divorces was the lowest in the cohort married when the husband was 23 to 32 years of age than in the cohorts with other ages at marriage in all the birth cohorts examined.

Age Factors↗
PubMed1998

Concurrent comparison of endoluminal versus open repair in the treatment of abdominal aortic aneurysms: analysis of 303 patients by life table method.

PURPOSE: The aim of this study was to compare the outcome of consecutive patients with abdominal aortic aneurysm (AAA) treated concurrently by open operation and endoluminal intervention by the same surgeons during a defined interval. METHODS: Between May 1992 and May 1996, 362 consecutive patients with AAA underwent repair. Fifty-three patients who underwent open operations for ruptured AAA plus two patients who underwent endoluminal repair of false AAA and four patients who underwent secondary endoluminal repair of AAA were excluded, leaving 303 patients who underwent elective repair of true AAA in the study. The elective operations were conventional open repair (OR) in 195 patients (151 men, 44 women; mean age, 69 years) and endoluminal repair (ER) in 108 patients (100 men, 8 women; mean age, 70 years). The decision to perform ERwas based on comorbidities that precluded open repair (n = 48) and patient choice (n = 60). Graft configuration in the open repair group was tubular (n = 180) and bifurcated (n = 15), and in the ER group tubular (n = 48), aortoiliac/femoral (n = 25), and bifurcated (n = 35). All procedures were performed in the operating department, and radiographic guidance was used in the ER group. Follow-up was by interview, examination, and telephone. In addition, contrast-enhanced computed tomography was performed within the first 10 days after operation, 6 months and 12 months after operation, and then annually thereafter in the ER group. Outcome measures were successful exclusion of the aneurysm sac from the general circulation and survival. Data were analyzed by the life table method. Other outcome measures were length of hospital stay, length of intensive care unit stay, and operative blood loss. RESULTS: No significant difference was found between the perioperative mortality rate for OR (11 deaths [5.6%] in 195 patients) and ER (six deaths [5.6%] in 108 patients). Three of the six deaths in the latter group occurred in patients with successful ER, and three occurred in 18 patients with failed ER who were converted to OR. Similarly, no significant difference was seen in the survival rate between the endoluminal and open repair groups when analyzed by the log-rank test (p = 0.14). The rate of graft failure, however, was significantly higher in the ER group than in the OR group (Fisher's exact test, p < 0.001). Success in the ER group was defined as continuing graft function without endoleak or conversion to open repair. Kaplan-Meier curve for graft failure times for the endoluminal group revealed a 3-year graft success probability of 70%. CONCLUSIONS: This study suggests that ER is safe, sharing the same perioperative mortality risk as OR despite 44% of the ER group being rejected as unfit for OR. Conventional open repair is the most reliable method of successfully managing AAA. The endoluminal method, however, results in shorter length of hospital stay, shorter length of intensive care unit stay, and less blood loss than the open method. Patients who opt for the endoluminal method of repair should be made aware that the minimally invasive technique carries the disadvantage of a higher failure rate.

Aged↗
PubMed1998

Importance of graft configuration in outcome of endoluminal aortic aneurysm repair: a 5-year analysis by the life table method.

AIM: The aim of this study was to determine the influence of graft configuration on the outcome of endoluminal repair of abdominal aortic aneurysm (AAA). METHODS: The 5-year study period extended from May 1992 to May 1997 and included analysis of patients undergoing endoluminal AAA repair in the first 4.5-year period with a minimum follow-up period of 6 months. Between May 1992 and November 1996 136 patients underwent endoluminal AAA repair. Two patients who had endoluminal repair of anastomotic AAA and six patients who had secondary endoluminal repair of AAA were excluded, leaving 128 patients in the study group. There were 117 males and 11 females with a mean age for the group of 71 years. The configuration of the grafts was tubular aortic (T) (n = 50), tapered aortoiliac/femoral (AI) (n = 24) and bifurcated (B) (n = 54). Patient characteristics and co-morbidities were similar in the three groups. The procedures were performed in the operating room under radiographic control. Follow-up was complete and consisted of regular physical examination and contrast enhanced computed tomography. Outcome measures were perioperative mortality rate, need for conversion to open repair, presence of early and late endoleaks, successful exclusion of AAA from the circulation, and survival. Data were analysed by the life table method. RESULTS: There was no significant difference in perioperative mortality for T (4%), AI (4%) and B (5.5%) configuration of endograft. Outcome for T, AI, and B configurations was respectively: primary conversion (%) 8, 12, 13; early endoleaks (n =) 5, 0, 1; late endoleaks (n =) 7, 0, 1. The overall incidence of failed procedures throughout the study period was higher in tube grafts compared with non-tube (aortoiliac and bifurcated) grafts (p < 0.05). Kaplan-Meier curves demonstrated a success probability at 40 months of 50% for tube grafts and 80% for non-tube grafts. However, a comparison of the time to procedure failure between tube versus non-tube after adjusting for competing risks (death without prior graft failure) was non-significant (p = 0.14). CONCLUSIONS: The poor mid-term outcome for tube prostheses requires a reassessment of the criteria for selecting this configuration. It would be unwise to abandon the use of tube prostheses entirely in endoluminal repair. With increasing information on mid and long-term outcome of endoluminal AAA repair it is likely that there will be an increasing acceptance of treating smaller AAA while they are still suitable for treatment by the endoluminal method and most likely with tube grafts. A tightening of the criteria for using tube prostheses would seem sensible. In particular, the minimum length of distal neck required for endoluminal tube graft repair should be increased to the 2-2.5 cm range.

Aged↗
PubMed1988

Estimating the age-at-onset function using life-table methods.

In the analysis of dominantly inherited diseases, the age-at-onset function is often estimated from the observed age-at-onset distribution of cases. This estimate is confounded with the age distribution of the population from which the cases were sampled and is accurate only if there are no competing causes of death. In this paper, we present a straightforward method for calculating a more accurate age-at-onset function under etiologic heterogeneity. We use the life-table approach and survival analysis methods. This method is illustrated using data on first-degree relatives of probands from two sets of families with high cancer incidence: one with breast/ovarian cancer and the other with colon cancer. A comparison of the estimated age-at-onset function obtained by the two methods is presented. In both cases, colon cancer as well as breast/ovarian cancer, the estimates of onset probabilities based on proportion of cases, are consistently higher than those obtained by the life-table method. For breast/ovarian cancer, this difference is not as striking as it is in the case of colon cancer; nevertheless, the method using proportion of cases tends to give a lower estimate of the age-at-onset function (higher probability of being affected at lower age) than the life-table approach.

Actuarial Analysis↗
PubMed1982

Long-term results of trabeculectomy in the Japanese: an analysis by life-table method.

The records of a total of 427 eyes with various types of glaucoma treated by trabeculectomy were compiled from 10 institutions. The follow-up periods of these cases were from 3 months to 5 years. Simple statistics gave an overall success rate of 75% in controlling the intraocular pressure (IOP) below 21 mmHg. In 344 eyes followed more than 1 year, the IOP distribution showed that the IOP was between 14 and 19 mmHg in 47% of th 10 institutions. The follow-up periods of these cases were from 3 months to 5 years. Simple statistics gave an overall success rate of 75% in controlling the intraocular pressure (IOP) below 21 mmHg. In 344 eyes followed more than 1 year, the IOP distribution showed that the IOP was between 14 and 19 mmHg in 47% of th 10 institutions. The follow-up periods of these cases were from 3 months to 5 years. Simple statistics gave an overall success rate of 75% in controlling the intraocular pressure (IOP) below 21 mmHg. In 344 eyes followed more than 1 year, the IOP distribution showed that the IOP was between 14 and 19 mmHg in 47% of the eyes, and in only 2.3% was the IOP lower than 10 mmHg. The probability of failure, i.e. the mean IOP being higher than 20 mmHg for more than 3 months, was calculated by a life-table method, which takes diversity in the follow-up period into account. An analysis of the cumulative failure probability by Weibull distribution function showed that the time course of failure in the IOP control is of an early failure type; the majority of failure occurred within one year. The final failure probability after the follow-up period of 5 years was 0.42 in primary open-angle glaucoma and 0.48 in primary angle-closure glaucoma, but it was 0.65 in congenital glaucoma. It was shown that the failure probability after the first trabeculectomy is lower in the older age group than in the younger age group. The second trabeculectomy on the same eye showed a higher failure probability than the first intervention.

Actuarial Analysis↗
PubMed1978

Robustness of life table methods in large populations--a study by computer simulation.

The robustness of the product life table estimator of the survival function was studied for large populations under perturbations in the age distribution, changing levels of mortality and changing patterns of fertility. A macrosimulation system, based on a class of stochastic population models called generalised age-dependent branching processes, was used to carry out the numerical investigations. Aside from drastic perturbations in the age distribution and changes in levels of mortality, the product life table estimator of the survival function was found to be robust in large populations, under a variety of conditions.

Age Factors↗