Biomedical subjects

K Aretz

Publications and source records attributed to K Aretz.

7 recordsLinked to original sources

PubMed1999

The effect of smoking on influenza, influenza vaccination efficacy and on the antibody response to influenza vaccination.

We examined the relation between cigarette smoking and (1) the occurrence of influenza, (2) the efficacy of influenza vaccination and (3) the antibody response to influenza vaccination in fifteen family practices in South-Limburg, the Netherlands, during the influenza season 1991 1992. Data were used from a randomized double-blind placebo-controlled trial into the efficacy of influenza vaccination in which smoking status was measured 10 weeks after the start of the trial. A total of 1838 subjects aged 60 years or older, of whom 1531 subjects (321 smokers, 1152 non-smokers and 58 cigar/pipe smokers) who returned the smoking questionnaire and were not previously vaccinated, were used in the analyses. The main outcome measures were serological influenza (fourfold increase of antibody titre between 3 weeks and 5 months after vaccination); clinical influenza as determined by criteria of the Dutch Sentinel Stations from self reported symptoms in postal questionnaires 10 weeks and 5 months after vaccination; increases after vaccination and decreases after 5 months in logarithmic titres of antibody against the vaccine strains. No relation between smoking and either serological or clinical influenza was found, although the risk for serological influenza was slightly (not significantly) elevated in smokers compared to non-smokers. A statistical interaction was found between smoking and vaccination when serological influenza was the outcome measure indicating that the efficacy of vaccination was greater in smokers than in non-smokers (comparison of model with and without interaction; likelihood ratio test, p < 0.0001). This finding is supported by a greater titre rise 3 weeks after vaccination for two out of four strains, but not by the antibody response after vaccination in previous studies on influenza and other infectious diseases. Also, this possible difference of immunogenicity is not reflected in a better protection for clinical influenza. The rise in antibody titre 3 weeks after vaccination was higher in smokers for A/Singapore/6/86 and B/Beijing/11/87, but not for the other two strains. Decline in titres after 5 months was similar for smokers and non-smokers. We conclude that smoking has no clinical or preventive significance for risk of influenza in the elderly.

Aged↗

PubMed1999

[Renal tumor embolization].

Today the relevance of renal tumor embolization is not determined only by the technical and clinical success of the method. Progress in diagnosis of early stages of renal carcinomas as well as the improvement of both surgical techniques and anesthetic procedures have lead to a change in the selection of patients for embolization. Preoperative embolization of advanced renal cell carcinomas with tumor thrombus into the vena cava or of T4 tumors is now an established clinical procedure. The complete occlusion of the vascular bed of the tumors leads to a considerable reduction in intraoperative blood loss and to simplification of the surgical preparation. By using Ethibloc for embolization, palliation of a hemorrhage or of tumor-related pain in inoperable patients is usually successful. Although local control of the tumor disease, including complete tumor ablation, is achieved by embolization, the median survival rate of our palliatively embolized patients is only 3.5 months. This short life expectancy in the group of inoperable patients has to be acknowledged individually in patients considered for palliative embolization who are free of symptoms related the tumor.

Aged↗

PubMed1999

Assessment of practicing family physicians: comparison of observation in a multiple-station examination using standardized patients with observation of consultations in daily practice.

PURPOSE: Looking for a valid, reliable, and feasible method to collect data on the performances of practicing family physicians, the authors compare the measurement characteristics of a multiple-station examination (MSE) using standardized patients with those of a video assessment of regular consultations in daily practice (practice video assessment, PVA). METHOD: In a cross-sectional study, consultations of 90 family physicians were videotaped both in an MSE and in their daily practices. Peer-observers used a validated instrument (MAAS-Global) to assess the physicians' communication with patients and their medical performances. The physicians were randomly divided into two groups, comparable for demographic characteristics, and half underwent the assessments in reverse order to test for time-order effects. Content validity, criterion validity, reliability, and feasibility of the two methods were compared. RESULTS: Content validity of the PVA was superior to that of the MSE, since the domain of general family practice care was better covered. Observed participants judged the videotaped practice consultations to be "natural," whereas hardly any family physician, after reviewing the videotaped consultations of the MSE, recognized his or her usual working style. Specific criteria made it possible to standardize real practice. Concerning criterion validity, only the medical-performance components of the two methods correlated. No correlation was found for the communication components. Real-practice performance proved to be less influenced by observation than was performance during the MSE. The reliabilities of the two methods, expected to be better in the controlled MSE, were comparable. The administration of the PVA was more flexible, less costly, and better accepted by the family physicians than was that of the MSE. CONCLUSION: Assessment for quality improvement of family physicians' practices by video observation in daily practice is superior to video assessment in a simulated setting using standardized patients.

Adult↗

PubMed1998

The predictive value of influenza symptomatology in elderly people.

OBJECTIVE: We aimed to determine the complex of symptoms which has the highest predictive value for the diagnosis of influenza. METHOD: A questionnaire study with questions regarding the symptomatology of influenza among patients aged 60 and older (n = 1838). Thirty-four participating GPs recorded the symptomatology of patients who came to their general practice with influenza-like complaints. The validity of the diagnostic conclusion of the GP, as well as the diagnostic validity of the criteria of the International Classification of Health Problems in Primary Care (ICHPPC-2) and the Sentinel Stations in The Netherlands, was determined with the help of the predictive value and odds ratio, using serologically confirmed influenza as the gold standard. The same method was used to determine which complex of symptoms has the highest predictive value for influenza. The results were verified using logistic regression analysis. RESULTS: The predictive value of the diagnostics of the GP amounted to 35%. The predictive values of the diagnostics according to the criteria of the two classification methods were 24% (Sentinel Stations) and 18% (ICHPPC-2). Of the individual symptoms, the combination of fever, coughing and acute onset had the highest predictive value (30.3%) for the diagnosis of influenza. CONCLUSION: It is recommended that the criteria of the Sentinel Stations in The Netherlands and the ICHPPC-2 be adapted in the following way: influenza is likely if, out of the entire complex of symptoms, at least fever, coughing and an acute onset occur.

Acute Disease↗

PubMed1998

Structure and process: the relationship between practice management and actual clinical performance in general practice.

OBJECTIVES: The precise relationship between practice management (structure) and the doctor's actual performance (process) in general practice is tenuous. Analysis of their mutual relationship may yield insight into the way they contribute to outcome and into corresponding assessment procedures. METHOD: In a cross-sectional study, consultations of 93 GPs were videotaped in their own practice and assessed by peer-observers on medical performance and on communication with patients, followed by a practice visit by a non-physician observer using a validated Visitation Instrument to assess Practice management and organization (VIP). Pearson correlations (observed and disattenuated for unreliability of the instruments) between scores on 22 practice management dimensions and scores of 16 selected cases on medical performance and communication were calculated. The predictive value of specific practice management aspects for actual performance was determined by multiple regression analysis, with performance scores as dependent variables and scores on the 22 management dimensions and GPs' professional characteristics as independent variables. RESULTS: Nine practice management dimensions correlated significantly with medical performance and so did five dimensions with actual communication. Overall, most associations were weak. Combined with demographic variables (age for medical performance and working single-handedly for communication), 26% of variance in medical performance scores could be explained by only three practice management dimensions. One practice dimension (delegation of medical tasks to the practice assistant) explained 11% of variance in communication with patients. Organization of quality assessment activities explained most of the variation in medical performance. CONCLUSIONS: Practice management (structure) and actual performance (process) seem to be largely autonomous constructs. Quality improvement and assessment activities should emphasize that practice management is different from actual performance. Structure and process may contribute to patient outcome independently of each other.

Adult↗

PubMed1994

Immune response to influenza vaccination of elderly people. A randomized double-blind placebo-controlled trial.

The objective of this study was to determine the immune response to influenza vaccination in elderly people, using a randomized, double-blind, placebo-controlled trial. Venous blood was taken from 1838 people aged 60 years and older, prior to injection with the influenza vaccine or a placebo. A second blood sample was taken three weeks later. The antibody reaction was measured by comparing the geometric mean titre and the percentage of participants who had a protective antibody titre before and after vaccination and for all sera of each strain. A protective antibody titre was found in 43-68% of those who had received the vaccine, depending on the strain investigated. Patients potentially at risk showed a response similar to the other participants. We conclude that influenza vaccination in elderly people provides a reasonable to good immune response. Research is needed on whether a good immune response decreases the incidence of influenza.

Aged↗

PubMed1993

Adverse reactions to influenza vaccine in elderly people: randomised double blind placebo controlled trial.

OBJECTIVE: To assess the frequency and type of side effects after influenza vaccination in elderly people. DESIGN: Randomised double blind placebo controlled study. SETTING: 15 general practices in the southern Netherlands. SUBJECTS: 1806 patients aged 60 or older, of whom 904 received influenza vaccine and 902 placebo. MAIN OUTCOME MEASURES: Adverse reactions reported on postal questionnaire completed four weeks after vaccination. RESULTS: 210 (23%) patients given vaccine reported one or more adverse reactions compared with 127 (14%) given placebo. The frequency of local adverse reactions were 17.5% in the vaccine group and 7.3% in the placebo group (p < 0.001). There was no difference in systemic adverse reactions (11% v 9.4%; p = 0.34). In general, men reported fewer side effects than women. CONCLUSION: Only local side effects were more common in vaccinated patients and all side effects were mild.

Age Factors↗