Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cohort Analysis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed2004

A nested case-control study of influenza vaccination was a cost-effective alternative to a full cohort analysis.

OBJECTIVE: In the absence of trial results that are applicable to the target population, nested case-control studies might be an alternative to full-cohort analysis. We compared relative and absolute estimates of associations in an influenza vaccine study using both designs. STUDY DESIGN AND SETTING: Data from elderly persons enrolled during six consecutive influenza seasons were used (147,551 person-periods). The endpoints "hospitalization for pneumonia or influenza" (P&I) or "death" were used combined and separately to define three types of cases. Controls for the case-control samples were randomly selected from the remainder of the total cohort at different ratios (1:1 to 1:4). Logistic regression analysis was used to assess adjusted vaccine effectiveness (VE). Sampling fractions were used to determine the number needed to treat to prevent one outcome. Receiver-operator-curve analysis was conducted to estimate the area under the curve (AUC) as a measure of discriminative capacity of the prognostic model. RESULTS: In all, 978 P and I hospitalizations and 1,339 deaths were observed. The adjusted estimates of relative estimates (VE, AUC) and their corresponding 95% confidence intervals were virtually the same using both study designs, notably when the case-control ratio was high (1:4). CONCLUSION: A nested case-control design can provide valid and precise estimates of associations and is a cost-effective alternative for full-cohort analysis.

Aged↗
PubMed1992

The effect of X-irradiation on cell cycle progression and chromatid aberrations in stimulated human lymphocytes using cohort analysis studies.

Stage sensitivity for the production of chromatid-type aberrations and mitotic delay has been investigated in a stimulated human lymphocyte population, following an absorbed dose of 1.5 Gy 250 kVp X-rays. BrdU replication banding was used to obtain a fine analysis of the cell cycle and to permit cohort analysis. Fluctuations in yield with sample time were found for all aberration categories, but these could not be related simply to either the developmental stage of the cells at time of exposure, or to the time-to-run to metaphase. In general G2 and late S cells had higher aberration yields than early S and pre S cell populations. Mitotic delay and perturbation at this dose extends to all sub-phases of S and is as great, if not greater, in the earliest S cells as it is in G2.

Cells, Cultured↗
PubMed1977

A cohort analysis of pancreatic cancer, 1939--1969.

Pancreatic cancer mortality in the United States was examined by cohort analysis for the period of 1939 to 1969. Birth cohorts at 5-year intervals were studied. White males and non-whites of both sexes showed a shift of the cohort mortality rate curves by age toward younger groups as birth cohorts went from 1870--1874 to 1900--1904. This shift disappeared in white males and diminished in non-whites of both sexes between the cohorts of 1890--1894 and 1900--1904. The shift in non-whites was larger than in white males so that although non-whites had lower rates than whites in earlier birth cohorts, their rates exceeded those of whites in the most recent cohort. In the search for environmental cause(s) of pancreatic cancer, exposure characteristics should be compatible with these observations.

Adult↗
PubMed1985

Attitudes toward social issues in health care: a cohort analysis.

Attitudinal change toward psychosocial issues in health care was tested through a cohort analysis of 190 nursing students at four successive undergraduate levels. The topics examined were: consistency and variability of attitudes toward social issues in health care and relationship between scale performance and age. Attitudinal change among nursing students at four successive undergraduate levels was tested in the present study using a modification of the Attitudes Towards Social Issues in Medicine (ATSIM) Inventory, an instrument composed of seven subscales dealing with various aspects of health care. Techniques used included analysis of variance and Levene's test of the equality of variances. The findings confirmed a process of professional socialization in nursing education with respect to the attitudes of nursing students toward health care issues.

Attitude of Health Personnel↗
PubMed1988

A multistage approach to the cohort analysis of lifetime lung cancer risk among steelworkers exposed to coke oven emissions.

A cohort analysis was performed to predict the lifetime lung cancer risk to a US or Canadian nonwhite male steelworker exposed to coke oven emissions. The procedure employed required that the lung cancer mortality (used for risk assessment) be estimated by addition of the excess to the background rates. The age-specific excess rates were obtained following selection of the proper excess risk function as implied by the multistage theory of carcinogenesis. A quantitative approach based on model fitting was used for selection of the excess risk function. The results show no evidence that coke oven emissions have a late stage carcinogenic effect. The indication that the agent acts as an initiator is moderate to weak. The number of carcinogenic stages involved was estimated to be four. Based on the assumption that exposure was set at a high concentration for 40 years with a starting age of 20 years, it was estimated that the lifetime risk through age 85+ years for a hypothetical US or Canadian nonwhite male oven worker could be as high as 0.40. This represents a 15-fold increase of the baseline risk.

Adult↗
PubMed1995

[Cohort analysis of population distribution change in Japan: processes of population concentration in the Tokyo region and its future].

"This paper aims at analyzing the relationships between net-migration and the transition of population distribution from the perspective of cohort analysis. The article consists of three parts: (1) review of...previous studies...; (2) evaluation of the transition of population distribution in Japan...; (3) presentation of a new projection method, where a basic concept of a new method for regional population projection and the preliminary trial for the Tokyo Region are discussed." (SUMMARY IN ENG)

Asia↗
PubMed2001

Laminoplasty versus laminectomy and fusion for multilevel cervical myelopathy: an independent matched cohort analysis.

STUDY DESIGN: A matched cohort clinical and radiographic retrospective analysis of laminoplasty and laminectomy with fusion for the treatment of multilevel cervical myelopathy. OBJECTIVES: To compare the clinical and radiographic outcomes of two procedures increasingly used to treat multilevel cervical myelopathy. SUMMARY OF BACKGROUND DATA: Traditional methods of treating multilevel cervical myelopathy (laminectomy and corpectomy) are reported to have a notable frequency of complications. Laminoplasty and laminectomy with fusion have been advocated as superior procedures. A comparative study of these two techniques has not been reported. METHODS: Medical records of all patients treated for multilevel cervical myelopathy with either laminoplasty or laminectomy with fusion between 1994 and 1999 at our institution were reviewed. Thirteen patients that underwent laminectomy with fusion were matched with 13 patients that underwent laminoplasty. All patients and radiographs were independently evaluated at latest follow-up by a single physician. RESULTS: Cohorts were well matched based on patient age, duration of symptoms, and severity of myelopathy (Nurick grade) before surgery. Mean independent follow-up was similar (25.5 and 26.2 months). Both objective improvement in patient function (Nurick score) and the number of patients reporting subjective improvement in strength, dexterity, sensation, pain, and gait tended to be greater in the laminoplasty cohort. Whereas no complications occurred in the laminoplasty cohort, there were 14 complications in 9 patients that underwent laminectomy with fusion patients. Complications included progression of myelopathy, nonunion, instrumentation failure, development of a significant kyphotic alignment, persistent bone graft harvest site pain, subjacent degeneration requiring reoperation, and deep infection. CONCLUSIONS: The marked difference in complications and functional improvement between these matched cohorts suggests that laminoplasty may be preferable to laminectomy with fusion as a posterior procedure for multilevel cervical myelopathy.

Adult↗
PubMed1999

Outcome of critically ill patients treated with intermittent high-volume haemofiltration: a prospective cohort analysis.

OBJECTIVE: To evaluate intervention and outcome in critically ill patients treated with high-volume haemofiltration (HV-HF). DESIGN: Prospective cohort analysis. SETTING: 18-bed closed format general intensive care unit (ICU) of a teaching hospital. PATIENTS: 30-month cohort of ICU patients treated with HV-HF. INTERVENTIONS: Intermittent high-volume venovenous haemofiltration. ENDPOINTS: Observed and predicted mortality in prospectively stratified prognostic groups. MEASUREMENTS AND RESULTS: Clinical and filtration data, Acute Physiology and Chronic Health Evaluation (APACHE) II, Simplified Acute Physiology Score (SAPS) II and the Madrid Acute Renal Failure (ARF) score and predicted mortality. A total of 306 patients were haemofiltrated (140 medical, 166 surgical), 52 % were oliguric. Mean APACHE II score was 31 (SD 8) and mean SAPS II score 60 (SD 16). Mean ultrafiltrate rate was 63 ml/min (SD 20). A median total of 160 litres (90 % range 49 to 453) were filtrated per patient, material costs were 565 ECU (90 % range 199 to 1514). ICU mortality was 33 %, hospital mortality 40 % [95 % confidence interval (CI) 34 to 45], predicted mortality by the ARF score 67 % (CI 66 to 69). Non-cardiac surgery mortality was 47 % (CI 39 to 54), 73 % (CI 70 to 76) predicted by APACHE II and 67 % (CI 64 to 70) by SAPS II. Observed mortality was significantly lower than predicted in all prognostic groups. The standardised mortality ratio (SMR) was no higher than the SMR in the overall ICU population. CONCLUSIONS: Mortality in HV-HF patients was lower than that predicted by illness severity scores, as was the case in all patients in our ICU. Treatment with HV-HF appears to be safe and feasible. The efficacy of HV-HF should be tested in randomised, controlled trials of suitable power.

APACHE↗
PubMed1993

Developments in drinking behavior in The Netherlands from 1958 to 1989, a cohort analysis.

Alcohol consumption in the Netherlands increased at a very fast rate from 1960 to 1975, especially among young men. The question is raised whether members of the cohort that started drinking during the 1960s show a lasting deviation from cohorts born earlier with respect to drinking behavior. Cohort analysis is used to assess the effects of aging, period and cohort membership on changes in abstinence, mean consumption and heavy drinking in the Netherlands in the last three decades. Social interaction theory (Skog, 1980) is used as an interpretative framework. Conclusions are that abstinence is related to aging, while mean consumption and heavy drinking are associated with period effects. Populations of men and women appear to change drinking behavior collectively. Results on women are more regular than those on men.

Adult↗
PubMed1994

Daily prognostic estimates for critically ill adults in intensive care units: results from a prospective, multicenter, inception cohort analysis.

OBJECTIVE: To develop daily prognostic estimates for individual patients treated in adult intensive care units (ICU). DESIGN: Prospective, multicenter, inception cohort analysis. SETTING: Forty-two ICUs at 40 U.S. hospitals with > 200 beds including 20 ICUs in tertiary care centers with major teaching activities. PATIENTS: A consecutive sample of 17,440 ICU admissions. MEASUREMENTS AND MAIN RESULTS: A series of multivariate equations were developed using the patient's primary reason for ICU admission, age, chronic health status, treatment before ICU admission, admission Acute Physiology Score, current day Acute Physiology Score, and change between the current and previous day's Acute Physiology Score. The equations were used to create daily risk predictions and cross-validated within the 17,440-patient sample. The single most important factor determining daily risk of hospital death during each of the initial 7 days of ICU care was the current day's Acute Physiology Score of the Acute Physiology and Chronic Health Evaluation (APACHE) III score. The admission Acute Physiology Score and change from previous to current day's Acute Physiology Score were also important, as were ICU admission diagnosis, age, chronic health status, and treatment before ICU admission. Equations incorporating these risk factors had receiver operating characteristics areas ranging from 0.9 on the first ICU day to 0.84 for patients remaining in the ICU for 7 days. The percent of cases with cross-validated predicted risks over 90% increased from 2.3% (n = 406) of cases on day 1 to 9% of all patients remaining in the ICU on ICU day 7 (n = 218). The 1,033 patients who had a daily risk estimate of > 90% during any of their initial 7 ICU days had a 90% mortality rate and represented 47% of all ICU deaths and 31% of the total number of hospital deaths. CONCLUSIONS: Equations using initial and repeated physiologic measurements provide a high degree of explanatory power for subsequent hospital mortality rate. These daily prognostic estimates deserve evaluation for their potential role in improving the process and outcome from clinical decision-making.

Adult↗
PubMed2001

Cohort analysis: W.H. Frost's contributions to the epidemiology of tuberculosis and chronic disease.

Although Wade Hampton Frost was not the first to develop cohort analysis, it was the post-humous publication of his study of age and time trends of tuberculosis mortality that directed attention to this method of analysis. Frost's developing interest in and contributions to the epidemiology of chronic disease are reviewed in connection with a summary of his professional career.

Chronic Disease↗
PubMed1984

Cohort analysis of malignant melanoma in five countries.

Vital statistics data on mortality from malignant melanoma from five countries are simultaneously fit by the method of cohort analysis. After the effects of geographic and temporal trends are removed, the proportion of deaths occurring in the younger age groups is found to be higher in females than in males. Relative increases in mortality rates by birth cohort are approximately equal in different regions and appear to be slowing down in recent years.

Adolescent↗
PubMed2000

Breast cancer survival and hormone replacement therapy: a cohort analysis.

Controversy exists regarding the safety of hormone replacement therapy (HRT) after a diagnosis of breast cancer. The objective of this study is to perform a matched cohort analysis to evaluate the impact of HRT on mortality in breast cancer survivors. Patients with breast cancer who received HRT after diagnosis of breast cancer were identified. Control subjects were identified from the regional cancer registry. Matching criteria included age at diagnosis, stage of breast cancer, and year of diagnosis. Controls were selected only if they were alive at the time of initiation of HRT of the matched case. Only subjects not included in a previously reported matched analysis were selected. One hundred twenty-five cases were matched with 362 controls. Ninety-eight percent (123/125) of the cases received systemic estrogen; 90/125 (72%) also received a progestational agent. The median interval between diagnosis of breast cancer and initiation of HRT was 46 months (range 0-401 months). The median duration of HRT was 22 months (range 1-357 months). The risk of death was lower among the HRT survivors; odds ratio 0.28 (95% confidence interval 0.11-0.71). This analysis does not suggest that HRT after the treatment of breast cancer is associated with an adverse outcome.

Breast Neoplasms↗
PubMed1995

Case-cohort analysis of case-coverage studies of vaccine effectiveness.

Evaluation of vaccine field effectiveness may be performed by combining surveillance data on incident cases with an immunization coverage survey. Although many methods have been used for the analysis of studies of similar design, they are not always desirable or optimal. The authors discuss these approaches and propose use of a case-cohort analysis for such a study design when appropriate. The case-cohort analytic approach is illustrated with data from studies of a vaccine for Haemophilus influenzae type b (Hib) disease in children living on a southwestern Native American reservation during 1988-1993.

Bacterial Outer Membrane Proteins↗
PubMedDate not supplied

Trends in smoking by birth cohort for births between 1940 and 1975: a reconstructed cohort analysis of the 1990 Ontario Health Survey.

BACKGROUND: Smoking patterns have changed markedly over the past 70 years. Previous studies have shown that examination of smoking patterns within birth cohorts can identify important changes in tobacco adoption and cessation. This paper examines temporal trends in the prevalence of smoking and the age of smoking adoption and cessation for birth cohorts born between 1940 and 1975. METHODS: The underlying data were obtained from the Ontario Health Survey (conducted in 1990), which used a multistage stratified area sampling strategy to obtain interviews on 29,843 people age 12 or older. Self-reported smoking histories were used as the basis for a reconstructed cohort analysis of prevalence rates. A life events methodology was employed to examine the age at starting smoking and the time of smoking cessation. RESULTS: There has been a steady drop in peak smoking prevalence for men. This trend appears to be continuing among the most recent cohorts. However, for women, peak smoking prevalence increased until the 1960 birth cohort, after which time the peak prevalence has been dropping. Prevalence of smoking was much higher for men then for women among the earlier birth cohorts but, by the 1960 cohort, the prevalence for men and women was essentially the same. Examination of the age of smoking onset reveals that there was a statistically significant interaction between sex and birth cohort on the relative risk of starting smoking. The rate of smoking cessation has increased uniformly across all birth cohorts among both men and women. CONCLUSIONS: This study confirms recent trends in smoking reduction and provides no evidence to suggest a diminution of the effect. Trends in recent birth cohorts of women are encouraging. There is a clear need for public health initiatives directed at older children and teenagers in order to further reduce the onset of smoking. Efforts to prohibit advertising directed toward minors, sponsorship of sporting and cultural events, and the sale of tobacco to minors should receive high priority.

Adolescent↗
PubMed1999

Persistence of susceptibility to measles in France despite routine immunization: a cohort analysis.

OBJECTIVES: This study examined the impact of French routine programs urging the combined measles-mumps-rubella immunization of 15-month-old children. METHODS: We applied a cohort analysis to surveillance data collected by general practitioners to estimate the cumulative incidence rate per 1000 unvaccinated children and the proportion of susceptible children, by age and for each birth cohort between 1985 and 1995. RESULTS: More than 70% of unvaccinated children born in 1985 and 1986 had measles by the age of 10. This incidence rate dramatically decreased after implementation of the routine measles-mumps-rubella immunization program in 1989, but the proportion of 5-year-olds susceptible to measles has not decreased appreciably. In 1996, more than 15% of the children born between 1990 and 1995 were susceptible. CONCLUSIONS: The measles vaccine coverage achieved by the French routine immunization program remains insufficient as regards reducing the number of susceptible children.

Age Distribution↗
PubMed2006

Trends in female circumcision between 1933 and 2003 in Osun and Ogun States, Nigeria (a cohort analysis).

The international movement against female circumcision gained momentum in the past two decades. Although recent studies report decline in the practice none has studied the cohort effect or provided plausible explanation for such decline. Changes in female circumcision occurring in two southwestern States of Nigeria between 1933 and 2003 were tracked in a cross-sectional survey using cohort analysis. 1174 female live births to 413 women were included in the analysis. About fifty-three percent of all females were circumcised. The prevalence dropped from 64.9% during the period 1933-60 to 25.7% for the period 2000-2003. For first order births, the corresponding rates were 58.8% and 25.0%. The decline for first-born females comes a decade before other birth orders. Age and education of mother are two main factors of the decline. Global consensus or legal enforcement plays secondary roles. Understanding how modernisation affects the decline in female circumcision should receive greater attention.

Age Factors↗