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Biomedical subjects

J A Knottnerus

Publications and source records attributed to J A Knottnerus.

At least 163 records · Page 9Linked to original sources
PubMed1991

[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.

Adolescent↗
PubMed1991

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.

Administration, Topical↗
PubMed1991

Discriminating ability of the erythrocyte sedimentation rate: a prospective study in general practice.

Despite its frequent use, little is known about the ability of the erythrocyte sedimentation rate to discriminate between 'pathology' (inflammatory diseases and malignancies) and 'no pathology' in general practice. This has been studied by following 362 patients who presented to their general practitioner with a new complaint, for which the general practitioner considered determination of the erythrocyte sedimentation rate to be indicated. The test was performed at the local hospital laboratory and the patients were seen again after three months, in order to establish the follow-up diagnoses. By comparing the test results with the follow-up diagnoses, combined with receiver operating characteristic curves and regression analysis, the erythrocyte sedimentation rate was found to have a reasonable discriminating ability with respect to malignancies and inflammatory diseases (sensitivity 53%, specificity 94%, positive predictive value 48%, negative predictive value 91%, odds ratio 15.1). The upper limit for the normal erythrocyte sedimentation rate should be set at approximately 12 mm hour-1 for men and 28 mm hour-1 for women, and needs no correction for age. It is concluded that the erythrocyte sedimentation rate still deserves a place in the general practitioner's daily routine.

Adolescent↗
PubMed1990

[The treatment of ankle edema in the elderly in family practice; when and how often are diuretics used?].

It has long been recommended that one should be careful in prescribing drugs for the elderly. However, it has been shown that more than 20% of those over 65 use diuretics. With advancing age this percentage increases. The sign of ankle oedema appears to be an important factor in the decision to prescribe diuretics. If the oedema is not caused by heart failure, chronic renal failure or hypoproteinaemia, the use of diuretics in ankle oedema is controversial. We used a questionnaire survey to obtain information on the opinions of Dutch general practitioners about the differential diagnosis and treatment of ankle oedema in the elderly. In the questionnaire we presented the case of a 68-year-old woman who complained of ankle oedema without any symptom or sign of heart failure. The questionnaire was sent to 200 Dutch general practitioners (response rate 64%). Chronic venous insufficiency was mentioned by 86% and heart failure by 12% of the responders as the most probable cause of the oedema. The treatment proposed by 59% was advice and (or) compression therapy without drugs, while 40% would have prescribed diuretics.

Aged↗
PubMed1990

Haematologic parameters and pregnancy outcome. A prospective cohort study in the third trimester.

The relationship between haematologic parameters and pregnancy outcome was investigated in a prospective study, taking important covariates into consideration. A questionnaire asking information about smoking, alcohol consumption and iron intake was completed by a consecutive series of 796 ambulatory singleton pregnant women at 31-32 weeks of gestation. Subsequently, haematologic parameters were measured. After delivery, birth weight, gestation length and blood pressure values during pregnancy were abstracted from the obstetricians' records. Low birth weight (less than 2.500 g) and preterm birth (less than 37 weeks), were significantly more frequently seen in women with high haemoglobin (greater than or equal to 8.0 mmol/l) or high haematocrit (greater than 38%) values, with Mantel-Haenszel odds ratios varying from 2.4 to 4.2. Also a high erythrocyte count (greater than or equal to 4.5/pl) was correlated with low birth weight, while for mean corpuscular volume (MCV) no such relationships were found. Pregnancy induced hypertension was positively associated with haemoglobin, haematocrit and erythrocyte count, but could not fully explain the relationships between these parameters and adverse outcomes. Using multiple logistic regression with low birth weight and or preterm birth as the dependent variable, the effect of haematocrit still was demonstrable after controlling for smoking, hypertension, parity, alcohol consumption and iron intake. These results are in agreement with the hypothesis that a higher blood viscosity is a risk factor for suboptimal placenta-perfusion.

Adult↗
PubMed1990

Comparing the quality of referrals of general practitioners with high and average referral rates: an independent panel review.

The quality of referrals of four general practitioners, two with high and two with average rates of referral to the department of internal medicine, was judged by an independent expert panel. The panel, consisting of two general practitioners and one specialist, reviewed a set of information about the referrals blindly and in random sequence. The same distribution of quality of referrals was found among the referrals of the two high referring general practitioners (n = 192) as among those of the general practitioners with average rates (n = 88); that is, 57% and 55% respectively, of the cases had clear medical indications for referral, while the data did not permit a conclusion in 15% and 10%, respectively, of the cases. Controlling for sex, age and status of the referral (first or repeat referral) did not alter the results. We conclude that using referral rates to judge referral quality is misleading. However, a blind and randomly performed panel review of referrals is a time consuming but feasible method of quality assessment.

Humans↗
PubMed1989

Symptoms and selection bias: the influence of selection towards specialist care on the relationship between symptoms and diagnoses.

Observations with respect to the relationship between symptoms and diseases can seriously be biased by selection phenomena. This selection may occur from the general population, via consultation behavior, diagnostic and therapeutic activities of the general practitioner, and by referral. Relationships may be suggested and reproduced even if they do not exist in unselected populations, as a product of diagnostic routines. Correction for selection bias can only be achieved by choosing proper comparison groups. While this can be done in a general practice setting, this is almost impossible after referral, as is demonstrated in this paper. Surprisingly, the most unbiased estimation of the relationship between symptoms and diseases after referral can be made from patient groups that are referred for reason unrelated to the disease under study. Definitive answers for the general practitioner can only be provided by prospective studies from a primary care setting. In the meantime, however, biased relationships can be maintained by teaching knowledge derived from a specialist experience.

Anemia↗
PubMed1989

Reliability of the erythrocyte sedimentation rate in general practice.

Because of the need for an accurate determination of the erythrocyte sedimentation rate (ESR), and because of the fact that many general practitioners frequently determine ESR in their own surgery, we investigated the reliability of the blood test in this setting. For this purpose, blood samples, obtained from the local hospital laboratory, were distributed, and the participating general practice centres were requested to determine ESR in each sample. A clinically important intra- and interpractice variability was found in the ESR values measured. The experiment was then repeated one year later under more standardized conditions, which resulted in a significant decrease in the intra- and interpractice variability (p = 0.04 and 0.003, respectively). Vibrations within the hospital building could not account for the systematically higher ESR values measured in the hospital laboratory. We conclude that a considerable increase in the quality of ESR performance in general practice can be achieved by means of relatively simple interventions.

Blood Sedimentation↗
PubMed1989

How well do general practitioners manage dyspepsia?

This paper reports the incidence of dyspepsia in general practice, the characteristics of patients, the types of complaints presented and the management of the dyspeptic patient by general practitioners. Fourteen general practitioners in the Maastricht region of the Netherlands studied 318 consecutive patients presenting with dyspepsia. Two questionnaires were used: one filled in by the patient (82% response), the other by the physician (100% response). The diagnostic conclusions which were established after three months of follow-up were compared with the diagnostic hypotheses at the initial consultation. The annual consultation rate for dyspepsia was calculated as 27 per 1000 registered subjects. One third of the patients had an earlier history of dyspepsia. Almost all patients (95%) complained of pain, and 37% had been suffering from pain for more than three months before consulting the general practitioner. The general practitioner prescribed medication in 70% of cases; less commonly the patient was referred for x-ray (14%), endoscopy (13%) or to a specialist (11%). A higher age was associated with a higher probability of referral, and with the finding of organic disease. A history of ulcer disease was strongly correlated with the diagnosis of an ulcer during the current episode. The overall concordance between the general practitioner's diagnostic hypothesis at the initial consultation and the diagnostic conclusion after three months of follow-up was 78%; it was highest when minor pathology was suspected. We conclude that dyspepsia is managed well in general practice and is only rarely associated with major lesions. Dyspeptic patients referred to a specialist therefore constitute a highly selected population.

Adolescent↗
PubMed1988

Haematologic parameters as risk factors for cardiac infarction, in an occupational health care setting.

It is still controversial, whether moderately high haematocrit (Ht) and haemoglobin (Hb) values are risk factors for coronary heart disease. Using the computerized data-system of the Periodical Medical Examination (PME) of Phillips' International Electrical Company, a case-control study was carried out. Cases were male workers (n = 104, from 50 to 60 years of age) who had suffered a first, non-fatal myocardial infarction, and who had had a PME prior (on the average 16 months) to the occurrence of infarction. For each case two age-matched healthy controls were selected from the PME-attendancy list (= 208). For each subject information was abstracted from the PME-records about haematologic parameters and covariates (smoking, cholesterol, blood pressure, pulse-rate, weight, height, FEV5, consumption of antihypertensive agents). After dichotomizing the haematocrit and haemoglobin values at their whole sample means (0.46 l/l and 9.7 mmol/l respectively) in "low" (lower than or equal to the mean) and "high" (greater than the mean), crude odds-ratio's of 2.7 (95% CI: 1.6-4.6) and 2.1 (95% CI: 1.2-3.6) were found for Ht and Hb respectively, when comparing "high" with "low" levels. The associations between Ht and Hb, and the occurrence of myocardial infarction were still present after controlling for covariates using multiple logistic regression models, entering the continuous variables with their exact values. After adjustment, mean corpuscular volume (MCV) also appeared to be correlated with infarction. Our results confirm the hypothesis that moderately high haematocrit and--to a lesser extent--haemoglobin and MCV-values are risk factors for the occurrence of myocardial infarction.

Blood Pressure↗