Recall bias in a case-control study of low birth weight.

The role of report/recall bias in case-control studies of low birth weight (LBW) was investigated in women who gave birth at a tertiary hospital. Prenatal exposure information reported at the postpartum interview was compared with that documented during pregnancy in obstetric records. 169 cases of LBW and 198 controls were selected. The two sets of information on case mothers and control mothers were compared, using the medical record as a reference. Kappa values were estimated. No trend was observed to increase/decrease the sensitivity and specificity of recall. Agreement on alcohol use was very low (kappa = 0.11 for case mothers and 0.03 for control mothers): on obstetrical records, only 12 mothers of cases reported habitual alcohol intake at the first prenatal care visit, whereas in the interview 69 said yes to the same question; in control mothers, the figures were 4 and 89 respectively. Odds ratios (ORs) of exposure estimated from the two sets of data did not differ importantly in 8 variables. Interview data yielded ORs for hypertension (8.39 versus 4.63), anemia (0.44 versus 0.99) that were farther from the null, and ORs in the opposite direction for alcohol (0.83 versus 1.61) and any drug (0.64 versus 1.42). In conclusion, given that OR figures are similar for most variables and no trend is observed in sensitivity/specificity, mothers of normal births can be an adequate reference group, using personal interviews to obtain information on lifestyle, and medical records for conditions.

Proportion of hospital deaths associated with adverse events.

OBJECTIVES: To determine the fraction of hospital deaths potentially associated with the occurrence of adverse events (AE). DESIGN: A paired (1:1) case-control study. SETTING: An 800-bed, teaching tertiary care hospital. PATIENTS: All patients older than 14 years admitted to the hospital between January 1, 1990, and January 1, 1991, were eligible. All 524 consecutive deaths (death rate of 3.74%) that occurred in the hospital comprised the case group. For each case, a control patient was matched for both primary diagnosis on admission and admission date. MEASUREMENTS: The proportion of hospital deaths associated with adverse events (defined as problems of any nature and seriousness faced by the patient during hospitalization, and potentially traceable to clinical or administrative management) was estimated from attributable risks adjusted for age, sex, service, severity of illness, length of stay, and quality of the medical record. RESULTS: For stays longer than 48 hours, the adjusted attributable risk for all adverse events was estimated to be 0.51 (0.40-0.61). When the data were stratified according to the category of adverse event, the attributable risks remained significant except for administrative problems. The greatest proportion of deaths associated with adverse events was observed for surgical adverse events [0.56 (0.38-0.71)] and nosocomial infection [0.22 (0.14-0.28)]. CONCLUSIONS: A significant proportion of intrahospital deaths were associated with AE. These results suggest the need to consider programs focused on the prevention of mortality from AE.

Nonincreased risk of nosocomial infection during a 22-day housekeeping personnel strike in a tertiary hospital.

BACKGROUND: From April 2-23, 1992, the housekeeping staff of the University of Granada Hospital was on strike. Measures were implemented to minimize the effects of the strike on patients' health and especially to diminish the risk of hospital infection. OBJECTIVE: To assess the risk of nosocomial infection during the housekeeping personnel strike. SETTING: An 800-bed, tertiary care hospital. METHODS: A case-cohort approach was used. One hundred forty-eight infected patients (with 184 hospital infections) were detected prospectively from March 1, 1992, to May 31, 1992. A sample of 459 of the base population (patients admitted during the same period) was selected. Information on relevant risk factors for hospital infection was abstracted from patients' clinical charts after hospital discharge. Crude odds ratios and adjusted (by proportional hazards model) relative risks (RRs) for the strike period were estimated. RESULTS: Risk of nosocomial infection did not increase during the strike period (multiple-risk factor adjusted RR = 0.99, 0.96 to 1.01/day of strike). Similar results were observed for major sites of infection (especially surgical wound) and major areas of the hospital (including gynecology, surgery, and intensive care). CONCLUSION: We concluded that there was no increase in the risk of nosocomial infection during the housekeeping strike.

Proportion of hospital deaths potentially attributable to nosocomial infection.

OBJECTIVE: To determine the fraction of hospital deaths potentially associated with nosocomial infection (NI). DESIGN: A matched (1:1) case-control study. SETTING: An 800-bed, tertiary-care, teaching hospital. PATIENTS: All patients older than 14 years who were admitted to the hospital between January 1, 1990, and January 1, 1991, were eligible. All 524 consecutive deaths that occurred in the hospital comprised the case group. For each case, a control patient was matched for primary admission diagnosis and admission date. OUTCOME MEASURES: The proportion of hospital deaths potentially associated with NI was estimated from the population attributable risk (PAR) adjusted for age, gender, service, severity of illness, length of stay, and quality of the medical record. RESULTS: For stays longer than 48 hours, the PAR for all NIs was estimated to be 21.3% (95% confidence interval [CI95], 16.8%-30.5%). The greatest proportion of deaths potentially associated with NIs was observed in patients with only one infection (PAR, 15.0%; CI95, 10.9%-22.6%) and bacteremia or sepsis (PAR, 7.7%; CI95, 4.6%-11.6%). CONCLUSIONS: NIs are associated with a large proportion of intrahospital deaths. This information may help clinicians and healthcare managers to assess the impact of programs for the prevention and control of NIs on intrahospital death.

Menopausal hormone replacement therapy and breast cancer: a meta-analysis.

A meta-analysis was performed to determine whether the scientific literature provides enough evidence that hormone replacement therapy after menopause increases the risk of breast cancer. Studies were located by MEDLINE, supplemented by a hand search of all the references in the articles located. The papers were graded as to quality. Those considered unbiased were combined using Woolf's method. Thirty-seven original studies were found: 23 case-control, 13 cohort, and one clinical trial. Overall, a small but statistically significant relative risk (RR) figure of 1.06 was calculated. Women who experienced natural menopause seemed to be at increased risk (RR = 1.13). A significant weighted RR was observed in current hormone replacement therapy users, especially in those who had natural menopause (RR = 1.63). A nonsignificant increasing trend was found between duration of hormone replacement therapy and breast cancer risk, although the opposite was seen when the association was analyzed by time since last use. These results imply that hormone replacement therapy could promote breast cancer.

Bacterial contamination of enteral feeds as a possible risk of nosocomial infection.

The degree of microbiological contamination in enteral diets was studied and the possible infectious complications that could arise in the patient after administration of an enteral feed were evaluated. Of the 208 diets studied, 56 (26.9%) were contaminated and 152 (73.1%) were sterile. Of the 56 contaminated diets, 11 could be used as delivered, but the other 45 required further modification. Of the patients who had received enteral feeding, 43 developed gastrointestinal symptoms in the first 24 h (fever, vomiting, abdominal pain and diarrhoea). Twenty-nine (67.4%) had received a contaminated diet and 14 (32.6%) an uncontaminated one. We conclude that contamination of enteral feeds may constitute a risk factor for nosocomial infection, and consider it necessary to carry out epidemiological surveillance in order to control the factors which may lead to contamination of enteral diets.

The risk of infection with hepatitis B virus in relation to length of hospital employment.

A sero-epidemiological study was carried out on a representative sample of employees of the Hospital Clinico 'San Cecilio' in an attempt to quantify the influence of the time spent working in the hospital on the risk of becoming infected by hepatitis B virus. The results show that the rate of infection by HBV is directly proportional to the length of employment in the hospital, with a probability of infection between 0.6% and 1.4% for each working year.

Influence of driver nationality on the risk of causing vehicle collisions in Spain.

STUDY OBJECTIVE: To estimate the association between driver nationality and the risk of causing a collision between vehicles in motion. DESIGN: Retrospective, matched by collision, case-control study. SETTING: Collisions that occurred in Spain during the period from 1990 to 1999 were studied. PARTICIPANTS: Responsible (case) and non-responsible (control) drivers identified in the databases of the Dirección General de Tráfico (General Traffic Directorate) who were involved in a collisions between two or more four wheeled vehicles in motion, in which only one of the drivers had committed a traffic violation. MAIN RESULTS: Crude odds ratios (ORs) for the effect of driver nationality on the risk of causing a collision were significantly higher for foreign drivers than for Spanish drivers, and ranged from a minimum of 1.19 (95% CI 1.09 to 1.29) for Portuguese drivers to a maximum of 2.06 (1.88 to 2.27) for British drivers. Corresponding adjusted ORs were slightly lower, but were still significantly higher than 1 for all nationalities except Italian, Belgian, and American (USA). Adjusted ORs were usually higher for collisions that occurred in urban areas than on open roads. CONCLUSIONS: Authorities responsible for traffic safety, and drivers in general, should consider foreign drivers in Spain at particularly high risk for causing collisions, especially in urban areas.

Epidemiology, therapy and costs of nosocomial infection.

In the current climate of cost containment and quality control, nosocomial infection is a worrisome adverse event in hospital care. Hospitalised patients require care for increasingly severe illnesses, and are therefore more susceptible to infection, especially by opportunistic micro-organisms. It is thus necessary to accurately assess and adjust for the severity of the underlying illness in studies of risk factors involved in nosocomial infections. The appearance of new diagnostic and therapeutic techniques provides novel opportunities for infection control and represents a constant challenge to hospital systems. The continuous selection of resistant flora, together with the identification of new pathogens, calls for a reconsideration of hospital policies regarding the dispensation of antibiotics. Epidemiological surveillance continues to be the most important aspect of attempts to monitor infection control programmes, and to identify changes in risk factors that may increase the infection rate. Among the major challenges now facing the infection control practitioner is the use of nosocomial infection rates as an indicator of quality of care. Awareness of infection statistics would serve as a stimulus to the prevention and control of infection, but would be useless if not accompanied by adequate systems to guarantee the comparability of data from different studies and centres. Suitably sensitive and specific surveillance systems should be developed, and the use of site-specific and procedure-specific infection rates adjusted for the patient's intrinsic risk should be encouraged.

Geographic variation of secular trends of breast cancer mortality in Spain.

Breast cancer mortality information contained in the available statistics derived from the Spanish death certificates has been reviewed. Mortality from breast neoplasms was grouped into three five-year periods: 1903-1907, 1931-1935 and 1975-1979. Age-adjusted rates were estimated for every province (n = 49) in each period, and confidence intervals for the standardized mortality ratios and adjusted rates were calculated. Results are presented with maps of Spain that illustrate provincial contrasts in each period. Secular breast cancer mortality trends in the provinces are discussed in comparison with those of other countries. Furthermore, values are compared with the geographical distribution of risk factors, the aim being to formulate hypothesis explaining the observed contrasts and suggesting some future research lines.

Oral contraceptives and breast cancer. A meta-analysis.

Since the relationship between oral contraceptive use and breast cancer has not been consistent we undertook a meta-analysis of studies published to date. Papers were located by searching the MEDLINE data base, supplemented by a hand search of all the references in the articles recovered. Studies were graded as to quality. Those judged as probably unbiased were included in the analysis. The method of Woolf was used to combine relative risks. Forty-seven studies were collected: 40 case-control and 7 cohort studies. Thirty-nine of these were considered unbiased. The main results observed were: RR was 1.06 (1.02-1.10) for all studies and 1.14 for premenopausal cancer. For premenopausal cancer, higher RRs were observed in women who early used oral contraceptives with a significant linear dose-response effect: 1.25 (1.10-1.44) in OC users before age 25, and 1.17 (1.06-1.30) in users before the first full-term pregnancy. We conclude oral contraceptive use may be a risk factor for premenopausal breast cancer. Limitations to our research are discussed.

PIP: 40 case control and 7 cohort studies of the link between oral contraceptives and breast cancer were combined in a meta-analysis by the method of Woolf to estimate overall relative risks. Articles were found by a Medline search from January 1966-June 1990, a hand search of the references, and a journal search for 1990. Papers were graded for bias by 2 blinded readers. The analysis of the 39 studies considered unbiased generated a global relative risk of 1.06, and an increased risk of 1.06, and an increased risk of 1.14 for premenopausal breast cancer. For premenopausal cancer, risks were 1.25 for use before age 24, and 1.17 for use before the 1st term pregnancy. A significant linear dose response was seen, in terms of months of exposure. There was an indication of latency, since risk estimates were higher from data collected after 1981. There was no evidence of a relationship between pill use and parity, family history, or history of benign breast disease. The dad are consistent with the theory that oral contraceptives can be acting as cancer initiators or promoters. There was not enough data to judge whether users of current lower dose pills have lower risks for premenopausal breast cancer. Future studies should address the difference between premenopausal and postmenopausal cancer.

A practical application of Rhame and Sudderth's formula on nosocomial infection surveillance.

We have conducted an epidemiological analysis of the utility of Rhame and Sudderth's formula--establishing a relationship between prevalence, incidence and duration of nosocomial infection--as an effective model in the surveillance of such infection. We carried out a follow-up study in a surgical service of our hospital on a sample of 799 patients admitted between January 1 and June 17, 1983 (24 weeks). We confirmed the condition of steady-state and were able to conclude that the Rhame and Sudderth model can have great utility when cross-sectional studies are performed with an adequate interval. We also concluded that the application of this model is not influenced by the size of the ward or zone of survey.

Changes in serum cholesterol in employees after three years of multifactorial intervention.

BACKGROUND: To assess long-term effectiveness of a multifactorial intervention at the work-site on serum cholesterol levels. METHODS: Individualized face-to-face counseling was given to 1,555 employees (76.7% male; mean age = 42.3 years) by occupational physicians at four work-sites. After 3 years, a blinded assessment of the adequacy of the intervention was done. Implementation of the intended intervention by physicians was assessed as adequate in two work-sites (927 employees) and inadequate in the other two (628 employees). Observed changes in serum cholesterol were analyzed in the followed-up individuals. Follow-up rates at each work-site were 78.6% and 44.5% for the adequate intervention, and 85.5% and 60.4% for the inadequate intervention. Changes in serum cholesterol were controlled for potential confounding factors (pre-test levels of risk factors, age, sex, body mass index, educational level, marital status, physical activity and alcohol consumption) by multiple linear regression procedures. RESULTS: When the intervention was adequately performed, serum cholesterol was significantly lowered with a mean reduction of 14.3 mg/dl (95% C.I.: 11.0 to 17.6) in those employees with baseline levels > or = 200 mg/dl. CONCLUSIONS: Adequacy of implementation of work-site programs determines their long-term effectiveness in reducing mean serum cholesterol levels.

[Evaluation of the cost of an intensive medicine unit. Relationship between the cost and the severity of the disease]. / Valoración del coste de una unidad de medicina intensiva. Relación del coste con la gravedad del enfermo.

BACKGROUND: The evaluation of the costs of intensive care is a subject of interest at present, due to the high resources required by this area of health care services and the rhythm at which these costs increase. Such an evaluation has rarely been carried out in Spain. The aim of this study was to quantify the cost of medical care to critical patients in an Intensive Care Unit (ICU) in addition to evaluate the relationship between the severity of the disease and the short term result of intensive health care. METHODS: A prospective study was carried out in 1,184 patients admitted (February 1985-February 1986) to the ICU of the Hospital General de Especialidades Virgen de las Nieves in Granada (Spain). Variables collected were the severity of the patient (APACHE II), therapeutic intensity (TISS) received, diagnosis on admission and state on discharge. A detailed and individualized evaluation was performed concerning the costs of hospital stay and treatment in the ICU. RESULTS: The cost per patient per day in the ICU was found to 54,438 pesetas in 1988. A significant association was demonstrated with age, severity, therapeutic intensity and the result of the stay in the unit, being much higher in the patients who died in the ICU, particularly in those in whom the prognosis "a priori" was good. CONCLUSIONS: A significant relation was found between the cost and severity of the disease, with the maximum costs being found in patients in whom survival was expected but who died and vice versa.

[Epidemiology of brucellosis in the Granada province (I). Occupational risks]. / Epidemiología de la brucelosis en la provincia de Granada (I). Riesgo profesional.

BACKGROUND: Brucellosis is a health problem in the Granada province. The major aim of the present study was to evaluate the professional risk to acquire brucellosis in Granada. METHODS: An epidemiologic study where the cases of brucellosis were found by active search was carried out. The study period was the year 1984. The patients (overall 804) were investigated in their residence area with a questionnaire where the major risk factors were considered. RESULTS: The disease was more common in males than in females (RR = 3); it had a significant tendency to increase with decreasing sizes of the urban nucleus (chi MH = 16.9, p less than 0.0001); and it had a significant relationship with the proportion of peasants and cattle workers in the region (r = 0.66, p less than 0.05). The professional group with the highest risk were veterinaries, in whom the disease was 31 times more common than in the rest of the population. CONCLUSIONS: Emphasis is made, in addition to other points, on the need to increase health education in the groups of more affected professionals.

[Changes in arterial pressure and smoking habit following 3 years of multifactorial intervention]. / Cambios en la presión arterial y en el hábito tabáquico tras 3 años de intervención multifactorial.

BACKGROUND: The feasibility of successfully reducing cardiovascular risk factors is supported by large studies. Nevertheless, controversy remains about the actual efficacy of some lifestyle interventions. This report assess the effectiveness of different levels of intervention at the work-site on blood pressure and smoking. METHODS: At the beginning of the program 1.193 men and 362 women were included in it. Individualized face-to-face counseling was given to employees by four different occupational physicians. After 3 years, 980 individuals remained in the study. The differences among the four groups allowed us to distinguish three different levels of intensity of interventions and a fourth group that was the reference one. Observed changes in blood pressure were compared using analysis of covariance. Adjusted odds ratio of smoking quit rates were calculated by logistic regression. RESULTS: Intensive intervention was significantly different from control group and the group of mild intervention. Moderate intervention was the only one to bring about a significant reduction of arterial blood pressures. This reduction was consistent with the lower threshold used in this group to classify diastolic blood pressure as high. Smoking quit rate was 22% for intensive and moderate interventions. Adjusted odds ratio for quitting smoking was 5.81 (95% CL 1.29-26.14) for moderate and 8.2 (IC 95% 1.75-38.46) for intensive intervention. CONCLUSIONS: A lower threshold for starting intervention measures on blood pressure is suggested to achieve better results. As the intensity of interventions was stronger, smoking quit rates were higher.

[Risk factors associated with falls in institutionalized elderly population. A prospective cohort study]. / Factores de riesgo de caídas en una población anciana institucionalizada. Estudio de cohortes prospectivo.

BACKGROUND: Falls in elderly subjects are a frequent cause of morbidity and mortality. The present study investigated risk factors associated with falls in institutionalized elderly subjects. PATIENTS AND METHODS: The subjects of this prospective cohort study were 190 persons aged 65 years or older, who were able to walk unassisted. We recorded sociodemographic variables, morbidity, drugs, functional capacity, cognitive status, gait and balance. Crude and adjusted density ratios (DR) were calculated and Cox proportional risk analysis was performed. RESULTS: A total of 121 falls occurred in 7 persons, for a fall rate of 0.75 per person per year. Independent risk factors identified with multivariate analysis were diabetes mellitus (DR = 3.6), slow gait (DR = 1.7), failed Romberg test (DR = 3.2) and fall(s) during the previous 12 months (DR = 1.9). Drugs that were associated with significant risk were digitalis, antiarrhythmics, neuroleptics, antidepressants and oral bronchodilators. A higher number of chronic diseases acted as a protective factor. CONCLUSIONS: The main risk factors associated with falls in elderly were easy to identify. Analysis of these factors can help to identify elderly persons with a high risk of falls, and thus focus appropriate preventive measures on these subjects.

[Infection by the human immunodeficiency virus among the Spanish population (I). Qualitative meta-analysis]. / Infección por el virus de la inmunodeficiencia humana en la población española (I). Metaanálisis cualitativo.

A meta-analysis of the original papers on human immunodeficiency virus (HIV) published in Spain was performed to better know the characteristics of HIV infection in Spain. Between 1985 and 1989, 67 investigations fulfilled the inclusion criteria. They were evaluated by means of a quantified questionnaire. The mean quality of the investigations was 44.65 +/- 1.5%. A bias in the selection was highly probable in 80% of the studies, whereas a bias in information and in confusion was less frequent (35.8% and 77.6%, respectively). The investigations of more quality were those carried out recently at the University in collaboration with other Institutions and with participation of sanitary personnel published in microbiologic journals.

[Infection by the human immunodeficiency virus in the Spanish population (II). A meta-analysis of the time and geographic trends]. / Infección por el virus de la inmunodeficiencia humana en la población española (II). Metaanálisis de las tendencias temporales y geográficas.

The aim of this research was to study the prevalence of infection by the human immunodeficiency virus (HIV) among the Spanish population. Due to the lack of available data we have applied meta-analysis techniques. We analyzed 67 original publications on this field appeared between 1985 and 1989. The prevalence of the illness has progressively increased among the risk groups (ADVP, homosexuals, prostitutes, heterosexual transmission) but not in hemophilic patients. The geographical distribution showed statistically significant differences being Barcelona as the province with the area of highest prevalence of the infection in ADVP and homosexuals.

[Proportion of disease attributable to tobacco in the province of Granada]. / Proporción de enfermedad atribuible al tabaco en la provincia de Granada.

BACKGROUND: Smoking is the main cause of preventable morbidity and mortality in Europe. The effect of smoking is not constant with the diseases related to it. The goal of this study is to estimate poblational etiologic fractions (PEF), as the proportion of disease attributable to smoking in the reference population, for those disease clearly related to smoking in Granada. METHODS: The PEF depend upon relative risk (RR) and the proportion of exposed subjects in the target population. Meta-analytic procedures, following the Woolf's method, were applied to estimate weighted RR between smoking and each one of the diseases studied. A survey on a random sample of all Granadian population to assess the prevalence of smoking was performed. RESULTS: The PEF were always higher for males than for females. In males, the highest figures were for lung cancer (85%) and chronic obstructive lung disease (84%); whilst in females lung cancer and peripheral artery disease reached the greatest figures, 55% and 51%, respectively. CONCLUSIONS: The figures obtained outline the need for improving antismoking campaigns and allow to quantify the maximum potential benefit to be got if smoking was quit by the Granadian population.