Biomedical subjects
J A Knottnerus
Publications and source records attributed to J A Knottnerus.
[Digoxin therapy in 24 automated family physician practices].
Since recent insights indicate that most patients with heart failure and a normal cardiac rhythm (HFNR) should not be treated with digitalis, we investigated the treatment policy of general practitioners in this respect. Our descriptive study consisted of a questionnaire followed by a computer based review of patient records of 14 family practices cooperating in the Registration Network of Family Practice (RNFP) and 10 'external' practices. All GPs (n = 51) received the questionnaire on the prescription policy of the GP and cooperating specialists, and on their experience with adverse effects of digitalis therapy. After 2-4 months the GPs of the RNFP (n = 41) received a floppy disc with an algorithm selecting from their problem lists patients with a registered diagnosis of heart failure. The external GPs (n = 10) received an algorithm selecting patients treated with digitalis, since their problem lists were not completely up to date. In all, data of 63,500 patients were examined. On anonymised standard forms, generated by the practice computer, the GPs provided data on the exact diagnosis, medication and adverse effects. Outcome measures of the study were: prescription attitudes (questionnaire) and actual digitalis use (in the selected cases). 33% of the GPs stated that they used digitalis as the preferred therapy of heart failure with normal cardiac rhythm; 30% of the 82 selected HFNR patients had digitalis, while in 42% of the 149 selected patients treated with digitalis a HFNR was registered. Adverse effects had been observed in 3 cases, but could not be excluded retrospectively in 70 cases (49%). Many GPs have not yet adapted their prescription behaviour to recently published insights. Development of a 'digitalis standard in general practice' is recommended.
Relation between quality of cervical smears and probability of abnormal results.
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Effect of feedback on test ordering behaviour of general practitioners.
OBJECTIVE: To assess the effect of feedback on the test ordering behaviour of general practitioners. DESIGN: Comparison of requests at two diagnostic centres, and internal comparison between tests which were discussed in feedback and tests which were not. SETTING: A diagnostic centre in Maastricht giving feedback and another elsewhere in the Netherlands (laboratory A) not giving feedback. SUBJECTS: All 85 general practitioners in the region of Maastricht, and all general practitioners in the region of laboratory A. MAIN OUTCOME MEASURES: Numbers of tests requested by general practitioners. RESULTS: Requests at the Maastricht diagnostic centre decreased soon after the onset of feedback whereas there was a persistent increase in requests at laboratory A. Tests that were discussed showed the strongest decrease (maximum 40%), though tests that were not discussed decreased as well (maximum 27%). CONCLUSIONS: Feedback on diagnostic requests may exert a strong influence on request behaviour. Four years after the onset of feedback the effects were still noticeable.
Plasma viscosity and erythrocyte sedimentation rate in inflammatory and non-inflammatory rheumatic disorders.
Plasma viscosity (PV) and erythrocyte sedimentation rate (ESR) are considered to reflect the complex of acute phase reactants in inflammations. Both tests were studied with regard to their ability to discriminate between inflammatory and non-inflammatory rheumatic diseases. PV and ESR were measured using the Coulter Viscometer II and the Westergren method, respectively. ESR was found to be a better parameter for rheumatoid arthritis and ankylosing spondylitis than PV, independent of the chosen reference values, age, gender and the hemoglobin level. ESR may still be regarded as an acceptable parameter for monitoring inflammatory rheumatic diseases.
The influence of referral patterns on the characteristics of diagnostic tests.
The discrimination of a diagnostic test--characterized by sensitivity, specificity, likelihood ratio and ROC curve--may be influenced by referral patterns of general practitioners. Symptoms and test results in particular will affect the probability of referral, while the degree of development of the pathological process directly influences the probability of positive test results. Using numerical examples, we analyse and discuss a few specific situations: (1) referral depends only on symptoms; (2) referral depends both on symptoms and on test results; (3) referral depends only on test results. In the first situation, test characteristics and predictive values are invariant over the strata of symptomatology, while in the third situation the predictive values are unchanged. If there is a positive relationship between positive test results and referral probability, overall sensitivity will increase while specificity and likelihood ratio will decrease. A general representation is given for the evaluation of the direction of change of the likelihood ratio as a function of referral probabilities. The shape of receiver-operating characteristic curves is less sensitive to bias, but at the level of specific cut-off points considerable changes may occur.
Chronic illness in the community and the concept of 'social prevalence'.
General practice is an important source of information on the occurrence and distribution of chronic disease in the population. In this study, the burden of chronic illness was expressed as different indices of prevalence. Data were provided by 42 general practitioners in 15 computerized practices, collaborating in the Registration Network Family Practices of the University of Limburg in the Netherlands. Morbidity data concerning the actual health status of 25,357 subjects, as recorded by their GPs, were classified following the International Classification of Primary Care using the diagnostic criteria of the International Classification of Health Problems in Primary Care-2-Defined. The most frequent single disease was asthma (3.5%), while locomotor problems represented the most prevalent category (8.3%). The overall prevalence of chronic disease was 29.4%, with a clear positive correlation with age and, to a lesser extent, with a lower educational level. The 'social prevalence' of chronic illness (including individuals related to chronically diseased patients via their households) could be measured in a subset of the database (n = 4577), and amounted to 56%. It is concluded that the role of the GP as a family doctor involved with chronic disease concerns the majority of the general population.
Diagnostic impact of the erythrocyte sedimentation rate in general practice: a before-after analysis.
Despite its frequent use and long history, little is known about the diagnostic impact of the measurement of the erythrocyte sedimentation rate (ESR) in general practice. We prospectively followed 362 patients who were seen by their general practitioner (GP) because of a new complaint, for which the GP wanted to know the ESR. The GPs recorded the most probable diagnosis, as well as their clinical judgements in terms of 'severe' and 'not severe', and the expected ESR values, before and after the determination of the ESR in the local hospital laboratory. Having compared the results before ESR determination with the results after, we conclude that ESR is valuable in reassuring the patient and the doctor when 'no pathology' is suspected rather than in confirming the presence of inflammatory diseases and malignancies.
Computerization of general practices and quality control. Blood glucose regulation in type 2 diabetics investigated in the Registration Network family practices.
The extent to which computerized medical administration facilitates quality control was studied using as an example the quality of blood glucose regulation in diabetics supervised by general practitioners in 11 computerized practices. Systematic use of the general practice computer rapidly provided an unequivocal answer that 37% of such patients were not regulated in accordance with the guidelines for type 2 diabetes mellitus of the Dutch College of General Practitioners. The extra workload for the participating general practitioners was minimal. Automated recording of problem lists, as applied in the general practices belonging to the Registration Network, facilitates access to data on chronic diseases and risk factors for purposes of research, quality control and quality assessment.
The diagnostic value of symptoms for the identification of patients with an increased risk of colorectal disease. A criteria-based analysis.
In most textbooks of gastroenterology, diseases with their symptoms are discussed. The exact diagnostic value of these symptoms, however, regarding the differentiation between organic and functional disease, is not mentioned. A criteria-based meta-analysis of the few existing studies in this field was done. From the 14 identified studies, there were two that did not find any significant symptoms. In the other studies the diagnostic value of colonic symptoms showed great variability. Methodological deficiencies in these studies are probably responsible for the latter. The generalization of these results into general practice is not straightforward and needs research in general practice patients.
Maxillary sinusitis in children.
In 169 children with a runny nose the difference between the group with rhinitis and those diagnosed as having sinusitis was indistinct. History and examination, and the results of radiology, ultrasound, the appearance of the sinus washings, the number of leucocytes in the washings, and the presence of pathogenic bacteria in the culture of the secretion from the nose and sinuses had little correlation with each other or with the clinical picture. In our view there is no marked difference between rhinitis and simple sinusitis, that is, mucosal inflammation of the maxillary sinus. This difference is also of no therapeutic relevance, and both diseases may be regarded as part of an upper airway infection. It is important to distinguish between sinusitis with and without empyema, because empyema must be treated differently. The latter disease produces distinct symptoms in the acute stage resembling ethmoiditis in children or maxillary and frontal sinusitis in adults. This type of sinusitis did not occur in our patients. Further investigation in children with a runny nose is indicated only in those with typical symptoms of an empyema.
Discriminating ability of plasma viscosity and erythrocyte sedimentation rate; a prospective study at the rheumatology out-patient department.
Measurements of plasma viscosity (PV) and erythrocyte sedimentation rate (ESR) are supposed to reflect the complex of acute phase reactants in inflammations. Both tests were prospectively studied at the rheumatology out-patient department with regard to their ability to discriminate between inflammatory and non-inflammatory rheumatic diseases in new patients (n = 235). PV and ESR were measured using the Coulter Viscometer II and the Westergren method, respectively. The Receiver Operating Characteristic curve for PV was slightly better than for ESR. However, at the higher cut-off points (PV greater than 1.81 mPa.s, ESR greater than 25 mm/l hr), sensitivities, specificities, predictive values and odds ratios were more favourable for ESR. Furthermore, since the costs of PV measurement are considerably higher, there is no reason for an implementation of PV in the daily routine of the rheumatologist at the outpatient department.
Computerized health information in The Netherlands: a registration network of family practices.
A registration network of family practices (Registratienet Huisartspraktijken) has recently been established in the Netherlands. Forty two general practitioners in 15 practices, with a patient population of 80,000 people, are using a general practice health information system to establish a central computerized anonymous database containing certain patient characteristics and all relevant health problems. By September 1990 patient characteristics and problem lists for 32,972 patients had been entered and a total of 94,476 health problems had been identified. The database has been set up primarily as a sampling frame, allowing researchers to identify patients with particular health problems. The database can also provide descriptive data on prevalence and incidence rates, fulfil a monitoring function and provide data for practice audit, medical education and health management.
Reactions of doctors to various forms of feedback designed to improve the sampling quality of cervical smears.
Three different forms of feedback designed to improve the sampling quality of cervical smears were tested in a randomized controlled trial among 179 physicians. The reactions of the doctors to the various interventions are reported as they appeared from their answers in a questionnaire. The influence of the interventions on the employed sampling technique is described on the basis of their answers to a telephone inquiry. The inclusion in laboratory protocols of an evaluation of the sampling quality of the submitted smears was largely appreciated, as was specific advice offered on indication. Monthly overviews comparing the performance of the individual doctor to that of his peers were esteemed by three out of four. Further information, help or training was requested more frequently than average by physicians obtaining inadequately sampled smears relatively often. The number of doctors using the combined spatula and Cytobrush method as sampling technique doubled during the study period.
Geographical variations in the sampling quality of cervical smears.
It is generally accepted that cervical smears are adequately sampled when they contain endocervical and/or metaplastic cells. An extensive literature search via MEDLINE and FAMLI for papers on cervical smears yielded 33 articles providing explicit information both on the country where the study was executed and on the relationship between the adequate sampling of smears and the sampling method used. The correlation between the geographic origin of cervical smears and the proportion of those smears that were adequately sampled was examined. The results were controlled for the sampling method. It was found that the proportion of adequately sampled smears reported in studies in the U.K. is exceedingly low, in contrast with the proportion reported from The Netherlands. The differences between the various countries studied are stable over different sampling methods. It is suggested that, in order to ameliorate the sampling quality of cervical smears, factors associated with the working conditions in particular regions also need be considered.
Cervical smear sampling quality.
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[An end to office hours for warts? A randomized study of the effectiveness of liquid nitrogen and of the Histofreezer].
OBJECTIVE: Comparison of the effectiveness of liquid nitrogen and of cryotherapy by means of the Histofreezer in the treatment of hand warts. DESIGN: Randomized therapeutic trial. SETTING: Six general practices in Limburg, The Netherlands. PATIENTS AND METHODS: Of the patients 43 (with 83 warts) were treated with nitrogen (if necessary twice) and 50 (with 108 warts) with the Histofreezer (if necessary 4 times), with a final control visit after 2.5 months. After a training session, the general practitioners performed the treatments and the observations. In these groups, 7 patients (with 18 warts) and 10 patients (with 20 warts) respectively did not fully comply with the protocol. At the start the number of warts per patient, their size, protruberance and localization were registered. Statistical analysis was performed by chi 2 test (unpaired case) in an intention to treat approach and of compliers only. OUTCOME MEASURES: Disappearance of warts, pain (on a 3-point scale), wounds, depigmentation. Non-compliers were asked by telephone if their warts had been cured. RESULTS: Of all patients 58% was cured by liquid nitrogen and 28% by Histofreezer (p = 0.01). Among the compliers these percentages were 67% and 35% of the patients (p = 0.01) and 66% and 49% of the warts (p = 0.08). The treatments were about equally effective in dorsal non protuberant and small (less than 5 mm) warts, and among young (less than 20 years) patients. CONCLUSION: The overall results of liquid nitrogen were better. The Histofreezer seems to be attractive in certain cases (e.g. children), but this should be the subject of further study.
The effectiveness of the hair-restorer "Dabao" in males with alopecia androgenetica. A clinical experiment.
In a randomized, double-blind trial the effectiveness of 6 months' use of a Chinese herb extract (Dabao) as a hair-restorer was studied on 396 males with alopecia androgenetica. The effect was evaluated by nonvellus hair counts, participants' opinions and a panel's judgement of a photo-report. Twenty-three participants withdrew prematurely from the study. In both the Dabao and placebo groups an increase in the amount of hair was observed; 133 and 109 hairs on a 5 cm2 marked area, a difference of 24 hairs (p = 0.03, one-sided). Participants as well as the panel reached a similar conclusion. Regarding cosmetic effect, 42% of the participants in the Dabao group and 37% in the placebo group reported positive results. The average panel score for the cosmetic result on a scale of -10 to +10 was 0.46 in the Dabao and 0.21 in the placebo group, a difference of 0.24 (p = 0.04, one-sided). It appears from our study that, although the cosmetic effect over 6 months is modest, Dabao does have a certain effect on the growth of nonvellus hair.