Determinants of the interval between the onset of symptoms and diagnosis in patients with digestive tract cancers.

The main objective of this cohort study was to analyze the influence of social factors on the interval from the onset of symptoms to diagnosis in the 217 patients with digestive tract cancer. From the clinical charts, the following information was extracted: date of the beginning of illness, dates of medical attendance, type and date of diagnostic tests, characteristics of the disease (symptoms, stage), and date of treatment. From personal interviews we gathered the data not present in the clinical chart: sociodemographic data, information about other underlying diseases, and variables related to lifestyle.

[Differences in the quality of Spanish clinical trials published in international periodicals and of the ones presented in general medicine periodicals with wide readership].

Background: The assessment of the methodological quality of controlled clinical trials (CCTs) carried out in Spain and published in international journals and the comparison with those published in widely read general journals of medicine (N Engl J Med, Lancet, JAMA, BMJ) may help establishing their limitations and improving quality in future studies.

Methods: Search in Medline of CCTs. Studies were evaluated according to a structured questionnaire (J Clin Epidemiol 1992; 45:225-265).

Efficacy of surveillance in nosocomial infection control in a surgical service.

Objective: The purpose of this study was to assess the efficacy of surveillance of nosocomial infection in infection control at a service of general surgery.

Design: A surveillance study that included 1483 patients with a prospective identification of nosocomial infection was carried out. Its results were discussed with the staff, and a program on nosocomial infection control was implemented.

Participation of epidemiologists and/or biostatisticians and methodological quality of published controlled clinical trials.

Study Objective: This study assessed several methodological aspects related to the quality of published controlled clinical trials (CCTs) in relation to the participation of an epidemiologist/biostatistician (E/B).

Design: Handsearch of CCTs published in four medical leading journals for 1993-1995.

Methods: Quality variables, abstracted from a review, were related to authors' specialties.

[Risk factors for nosocomial sepsis: a case-control study].

Background: The objective of this study was to identify the risk factors associated with the nosocomial sepsis syndrome according to the criteria of the American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference.

Patients And Method: A 1-year prospective case-control study matched for sex, age (+/- 5 years), and pre-infection hospital stay (+/- 1 day) was performed in a 1,200-bed university hospital. Cases were selected according to the above criteria.

Recreation in coastal waters: health risks associated with bathing in sea water.

Study Objective: To find out whether bathing in sewage polluted waters implies a danger to bathers' health and to determine the best microbiological indicator to predict the relation between bathing and the appearance of some symptoms.

Design: Cohort study.

Setting: City of Santander (north of Spain).

[Role of primary care teams in hospitalization of children under 2 years of age?].

Objective: To determine whether the structure of primary care teams on carrying out the healthy child health programme leads to a drop in the risk of admission to hospital of children under two, in comparison with the traditional clinic or out-clinic health system.

Design: Case-reference epidemiological study.

Cases: 40% of the children under 24 months admitted to paediatric or neonate floors of the Marqués de Valdecilla University Hospital.

[Hepatitis B vaccination. Indications of the post-vaccine serologic test and booster doses].

The standard anti-HBV vaccination elicits protective anti-HBs levels (above 10 UI/l) in most people. However, the effective duration of immunologic memory is not well-known. Consequently, the recommendations on the postvaccination follow-up are not uniform: from vaccination with no follow-up blood test (anti-HBs levels) to regular follow-up blood tests for all vaccines.

Epidemiology of surgical-site infections diagnosed after hospital discharge: a prospective cohort study.

Objective: To study postoperative infections in hospital and after discharge, and to identify the risk factors for such infections.

Design: Prospective cohort study, with telephone follow-up for 1 month after hospital discharge.

Setting: The general surgery service of a tertiary hospital in Spain.

Circulating CD8+ T cells in polymyalgia rheumatica and giant cell arteritis: a review.

Background And Objective: During the last few years, there have been several studies on T cell subsets in polymyalgia rheumatica (PMR) and giant cell arteritis (GCA), with conflicting results. Whereas some authors have found normal values of circulating CD8+ T cells, others have found a decreased number. Furthermore, in some studies, the level of CD8+ cells was found to be related to disease activity, and it has been proposed that a decrease of CD8+ T cells be used as a diagnostic criterion for PMR.

Competing risks analysis using Markov chains: impact of cerebrovascular and ischaemic heart disease in cancer mortality.

Background: A decrease in cerebrovascular disease (CVD) and ischaemic heart disease (IHD) mortality can produce an increase in mortality from other causes, even cancer. This problem is called the competing risks problem.

Methods: A Markov chain is used to analyse the interrelation between CVD, IHD and cancer mortalities in Spanish women in 1981 and 1994.

Competing risks in absence of independence: impact of AIDS on liver function failure mortality, and lung cancer on ischemic heart disease mortality.

The increase in lung cancer (LC) mortality can produce a decrease in mortality from other causes, including ischemic heart disease (IHD). This problem (called the competing risks problem) has been addressed usually assuming independence between the competing causes of death. Our purpose is to show that assuming dependence of causes of death allows obtaining a better estimation of cumulative mortality.

[Influence of parental smoking on pediatric hospitalization for respiratory illness among children aged less than 2 years].

Aim: To determine whether parental smoking increased the risk of hospitalization among children aged less than 2 years.

Design: Case-reference study conducted from April 1995-May 1996. The group of cases was composed of 40% of all the children aged 2 years or less years admitted to our hospital (n=392).

Epidemiological differences between sepsis syndrome with bacteremia and culture-negative sepsis.

Objective: To explore the association of putative disease markers and potential risk factors with the nosocomial sepsis syndrome.

Design: Prospective case-control study matched for gender, age, and length of preinfection hospital stay.

Setting: 1,200-bed tertiary-care center in Spain.

Applicability of two surgical-site infection risk indices to risk of sepsis in surgical patients.

Objective: To compare the ability of the Study of the Efficacy of Nosocomial Infection Control (SENIC) and the National Nosocomial Infection Surveillance (NNIS) indices to predict the development of nosocomial sepsis in subjects undergoing surgery.

Design: 1-year prospective case-control study.

Setting: A tertiary-care center in Spain.

[Comparison between several standard populations for age-adjusting].

Background: To analyse the effect the choice of reference population has on different indicators derived from mortality rates age-adjusting.

Methods: The mortality rates for different causes of death in Spain from 1971 to 1992 were adjusted by using four reference populations: Spanish populations from 1971 and 1992, the Standard European population and the standard world population. The results obtained with the four populations were compared by applying three indicators: difference between the rates of 1992 and 1971, ratio between the rates of 1992 and 1971 and annual percentage change between 1971 and 1992.

Comparison of the performance of two general and three specific scoring systems for meningococcal septic shock in children.

Objective: To evaluate the performance at admission to the pediatric intensive care unit (PICU) of five severity scores, two general (the Pediatric Risk of Mortality [PRISM] II and III scores) and three specific for meningococcal septic shock (Leclerc, Glasgow Meningococcal Septicemia Prognostic Score [GMSPS], and Gedde-Dahl's MOC score) in children with this condition.

Design: Multicenter, retrospective, cohort study.

Setting: The PICUs from four tertiary centers.

Analysis of risk factors for nosocomial sepsis in surgical patients.

Background: This study aimed to identify patients at high risk for developing sepsis following surgery according to criteria determined by the American College of Chest Physicians and the Society of Critical Care Medicine Consensus Conference on sepsis.

Methods: A prospective case-control study was performed in surgical patients in a tertiary care centre over 1 year. Patients were identified by a daily prospective surveillance.

[The measurement of inequalities in age of death: calculating the Gini Index based on mortality tables].

The Gini index has been used to gauge the concentration of different variables, including income, the mortality distribution and the spread of physicians. The use of the Gini index for gauging the inequalities in the age of death based on actuarial mortality data. For this purpose, the 1990 age and gender-related mortality figures for each Autonomous Community were used.

A comparison of several procedures to estimate the confidence interval for attributable risk in case-control studies.

The estimation of a confidence interval for attributable risk from the logistic model based on data from case-control studies is a problem for which an accepted solution is lacking. Two methods, one based on the delta method and one bootstrap on the population base, have been described but their accuracy has not been compared. We present two other methods, one based on a jack-knife approach and the other using a bootstrap on two samples (cases and controls).

[Biases in the study of prognostic factors].

The main objective is to detail the main biases in the study of prognostic factors. Confounding bias is illustrated with social class, a prognostic factor still discussed. Within selection bias several cases are commented: response bias, specially frequent when the patients of a clinical trial are used; the shortcomings in the formation of an inception cohort; the fallacy of Neyman (bias due to the duration of disease) when the study begins with a cross-sectional study; the selection bias in the treatment of survivors for the different treatment opportunity of those living longer; the bias due to the inclusion of heterogeneous diagnostic groups; and the selection bias due to differential information losses and the use of statistical multivariate procedures.

[Biases in meta-analysis].

The objective of the present article is to review the biases in meta-analysis. This procedure can be included within observational studies, and its biases follow the same classification: selection, information and confounding bias. Selection bias can always be present because of the impossibility of enumerating the reference population.