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Biomedical subjects

J A Knottnerus

Publications and source records attributed to J A Knottnerus.

At least 91 records · Page 5Linked to original sources
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

Morbidity in responders and non-responders in a register-based population survey.

BACKGROUND: Non-response analysis is often restricted to the influence of age, sex and socio-economic status on response status. In this study the health status of responders and non-responders was also compared. RESULTS: Responders were comparable to non-responders with regard to the number of diagnosed disorders as well as to the prevalences of disorders within body systems. Non-responders only showed psychological disorders more often. CONCLUSION: It is useful to assess the relation between non-response and morbidity patterns in other studies as well, in order to detect selective non-response and bias.

Adult↗
PubMed1998

Arrhythmias in general practice: diagnostic value of patient characteristics, medical history and symptoms.

BACKGROUND: Complaints possibly caused by arrhythmias are frequently seen in general practice. It is unclear to what extent such complaints can differentiate between arrhythmias and other pathology in general practice. OBJECTIVES: We aimed to assess the value of symptoms (a) in diagnosing arrhythmias in general practice and (b) in identifying patients with clinically relevant arrhythmias. METHOD: During a 2-year period, a structured history from 762 patients with new complaints possibly related to an arrhythmia was taken by the GP, and a transtelephonic electrocardiogram (ECG) was made. RESULTS: In 28.3% of the patients, arrhythmias were detected and 8.8% were clinically relevant. Several patient characteristics, symptoms and medical history findings have high predictive values in diagnosing arrhythmias. In the logistic regression analysis, age and, to a lesser extent, male gender, palpitations and dyspnoea during consultation and the use of cardiovascular drugs are associated with the presence of arrhythmias. In detecting clinically relevant arrhythmias the same parameters apart from gender are important, as well as a history of arrhythmias. The use of central nervous system medication and frequent psychosomatic complaints are negatively associated with the presence of clinically relevant arrhythmias. CONCLUSIONS: In general practice, patient characteristics, symptoms and medical history findings can be used in the detection of arrhythmias and the assessment of their severity. They can help in the decision of whether to make an ECG recording.

Adolescent↗
PubMed1998

Utility of ultrasound of the upper urinary tract in elderly men with indicators of obstructive symptoms or abnormal flow: how often can silent hydronephrosis be detected in general practice?

BACKGROUND AND OBJECTIVE: While the prevalence of hydronephrosis is very low in obduction studies, a prevalence of 3-13% is reported for patients with an obstruction who are listed for prostatectomy. In order to evaluate the usefulness of transabdominal ultrasound in primary care, we determined the occurrence of hydronephrosis in males with symptoms of urinary obstruction in a general practice setting. METHOD: A micturition questionnaire (a modified Boyarsky) was sent to all men of 55 years or more who were registered in 10 general practices in Maastricht, and was followed by an examination at their general practice. Men with obstructive symptoms and/or with a free-flow abnormality were examined in the hospital with transabdominal ultrasound in order to detect dilatation of the upper urinary tract. This ultrasound was repeated approximately 15 months later. RESULTS: At the first measurement, none of the examined men (n = 178) had hydronephrosis, and this was still the case for 94 men 15 months later. CONCLUSION: Renal ultrasound is not necessary in general practice for men with uncomplicated obstructive complaints.

Aged↗
PubMed1998

Economic evaluation of cholesterol-related interventions in general practice. An appraisal of the evidence.

STUDY OBJECTIVE: To investigate and evaluate published data on cost effectiveness of cholesterol lowering interventions, and how this information could be interpreted in a rational approach of cholesterol management in general practice. DESIGN: A systematic review of the literature. SETTING: No restriction on setting. MATERIALS: Papers reporting on the cost effectiveness or cost utility of prevention of (recurrent) coronary heart disease by reduction of hypercholesterolaemia in adults. MAIN RESULTS: Thirty nine studies, most cost effectiveness analyses, were included. In 24 studies drug interventions only were analysed. Costs of screening to target cholesterol lowering interventions to persons with hypercholesterolaemia were considered in nine studies. Adjustments of the efficacy of the intervention for community effectiveness were described in seven studies. In four studies life years gained were adjusted for quality of life. Despite large variation in the outcomes, there is a constant tendency towards a less favourable cost effectiveness ratio for intervening in persons without coronary heart disease compared with persons with coronary heart disease and for women compared with men. CONCLUSIONS: There is lack of data on cost effectiveness of cholesterol lowering interventions in the general practice setting. The cost effectiveness of cholesterol lowering in general practice deteriorates when all relevant costs are taken into account and when efficacy is corrected for community effectiveness. Cholesterol lowering intervention is more cost effective in men compared with women and in patients with coronary heart disease compared with persons without coronary heart disease. Considerations from cost effectiveness analyses should be incorporated into the development and implementation of national cholesterol guidelines for general practitioners. Standardisation of cost effectiveness studies is important for future economic evaluations.

Coronary Disease↗
PubMed1998

Determinants of doctor consultation for micturition problems in an elderly male population.

OBJECTIVE: To study which factors influence doctor consultation when a subject has micturition problems. METHODS: Postal questionnaire in an open population of older men (n = 1,695), followed by investigations in 10 general practices, including uroflowmetry. RESULTS: 25% of the men had micturition problems, of which 10-30% presented their symptoms to a doctor. Almost 60% experienced an influence of their micturition habits on activities of daily living. More than 85% of the men were not able to compare their micturition pattern with others. In multiple logistic regression, presentation to a doctor was independently associated with obstructive symptoms, dysuria, men defining their situation as a complaint, depressive mood, more frequent sexual desire and smoking. Many other factors which might play a role in diagnosis and timing of treatment were not found to influence consultation. CONCLUSION: Most men deal with micturition problems without consulting, although symptoms have a substantial impact on daily life. Consultation was associated with symptoms, psychological factors and smoking.

Aged↗
PubMed1997

Primary-care-based randomised placebo-controlled trial of antibiotic treatment in acute maxillary sinusitis.

BACKGROUND: The value of antibiotics in acute rhinosinusitis is uncertain. Although maxillary sinusitis is commonly diagnosed and treated in general practice, no effectiveness studies have been done on unselected primary-care patients. We used a randomised, placebo-controlled design to test the hypothesis that there would be an improvement associated with amoxycillin treatment for acute maxillary sinusitis patients presenting to general practice. METHODS: Adult patients with suspected acute maxillary sinusitis were referred by general practitioners for radiographs of the maxillary sinus. Those with radiographic abnormalities (n = 214) were randomly assigned treatment with amoxycillin (750 mg three times daily for 7 days; n = 108) or placebo (n = 106). Clinical course was assessed after 1 week and 2 weeks, and reported relapses and complications were recorded during the following year. FINDINGS: After 2 weeks, symptoms had improved substantially or disappeared in 83% of patients in the study group and 77% of patients taking placebo. Amoxycillin did not influence the clinical course of maxillary sinusitis nor the frequency of relapses during the 1-year follow-up. Radiographs had no prognostic value, nor were they an effect modifier. Side-effects were recorded in 28% of patients given amoxycillin and in 9% of those taking placebo (p < 0.01). The occurrence of relapses was similar in both groups (21 vs 17%) during the follow-up year. INTERPRETATION: Antibiotic treatment did not improve the clinical course of acute maxillary sinusitis presenting to general practice. For these patients, an initial radiographic examination is not necessary and initial management can be limited to symptomatic treatment. Whether antibiotics are necessary in more severe cases warrants further study.

Acute Disease↗
PubMed1997

Fitting a routine health-care activity into a randomized trial: an experiment possible without informed consent?

Due to possible methodological and practical problems, many researchers refrain from using a randomized controlled trial design to evaluate procedures already embedded in routine health care. We performed a randomized controlled trial on the effects of routine individual feedback on test ordering behavior of family physicians. The trial started after 4 years of feedback and lasted for 2.5 years. With some adaptations a randomized trial proved to be possible. In evaluating health-care procedures that cannot be blinded in a traditional way, asking full and study-specific informed consent may conflict with the validity of the design. In such studies, an alternative procedure is to be considered. Our trial, with doctors as study subjects, was held on an already accepted routine procedure (feedback). This made it possible to refrain from obtaining study-specific informed consent. Consequently, a Hawthorne effect and contamination of the trial arms through information leakage could be avoided. Justification and general criteria for not obtaining full and study-specific informed consent are worked out. In health-care research on the performance of doctors or on interventions into the quality of care, obtaining a general informed consent in advance is an acceptable alternative approach.

Diagnostic Tests, Routine↗
PubMed1997

Gender-related differences in non-epileptic attacks: a study of patients' cases in the literature.

Gender-related differences for disorders of consciousness other than true epilepsy usually point to a larger number of women suffering especially from non-epileptic attacks or pseudoseizures. Recently, sexual abuse has been suggested as a possible cause for this increased prevalence in women. It has, however, not been very clear if women have a different phenomenology of these type of seizures from men. In the present study, patients' cases as published in the literature are analysed in a detailed way, using a working classification by Betts et al to look for gender-specificity. Of the 62 cases, 76% concern women and 24% men; a percentage comparable to those published elsewhere. Ages range from 14 to 77 years-of-age, but 89% of patients are younger than 40. Sexual abuse was proven in 18 cases, all women. The phenomenology of the attacks was divided into tonic-clonic type and complex partial type of attack, or a combination of the two. Also, special types of attacks (swoons, tantrums, abreactive attacks and forthright simulation) were looked for. Males tended to suffer especially from tonic-clonic type seizures (80% of cases), while in women as many tonic-clonic type as complex partial type attacks were observed. Special types of attacks were observed at the same frequency in both sexes. The group of sexual abuse victims did not differ from the total group of women in this respect. The clinically more impressive nature of a tonic-clonic-type attack, that is more easily suspected to be 'real', might make this type of seizure a more male form of acting out. A prospective study on the incidence and phenomenology of pseudo-epileptic seizures in the general population is suggested to answer the new questions raised in this survey.

Abreaction↗
PubMed1996

[Home visits by community health nurses can contribute to the family practitioner's knowledge of elderly patients].

OBJECTIVE: To determine to what extent the general practitioner (GP) is aware of the health status and functioning of his elderly patients and in which areas this knowledge can be completed with the aid of community nurses. DESIGN: Cross-sectional, descriptive. SETTING: Department of General Practice. State University Limburg, Maastricht, the Netherlands. METHODS: A random sample of 59 patients aged 79 years and over, belonging to the population of a primary health care centre, were visited by community nurses. One patient was lost. The nurses inventoried the patients health complaints and their daily functioning by means of a structured questionnaire. Data from these home visits were compared with data from the same questionnaire, regarding the same patients, which the three GPs of the health centre had filled in on the basis of their medical records. RESULTS: Of the complaints recorded by the community nurses. 34% were not known to the general practitioners. This concerned mainly symptoms of depression, urinary incontinence, disabilities and handicaps of the musculoskeletal system. sleep disturbances, daily functioning and ability to cope. The main determinants of the ability to cope were impaired walking and to a lesser degree symptoms of depression. CONCLUSION: A structured interview of elderly patients by a community nurse yields substantial information about health problems.

Activities of Daily Living↗
PubMed1996

Somatization in frequent attenders of general practice.

The DSM-III-(R) definition of somatization disorder is too restrictive for use in general practice. A more comprehensive definition, the "somatic symptom index" (SSI) has shown good validity in open populations. However, a definition has to differentiate validly within a population of frequent attenders to be a useful diagnostic instrument in general practice. We studied a threshold of five complaints (nearly identical to the SSI) in 80 Dutch general practice patients. Patients were selected on age (20-44 years), history of back, neck or abdominal complaints, and on frequency of consultation- at least 12 consultations in the previous 3 years, corrected for consultations with compelling somatic reason for encounter. Prevalence of somatization in this group was 45%. Women had a 2 times higher risk of somatization. A relation with age was not found. Somatization was related to depressive complaints (relative risk 2.5) and probably also to anxiety. Somatizing patients consulted their general practitioner more often and had more health problems (especially psychic problems) than non-somatizers. These results support the validity of this definition. The distinction between our definition of somatization and somatization defined as a symptom of psychiatric (e.g. depressive or anxiety) disorder is emphasized.

Adult↗
PubMed1996

Unlocking patients' records in general practice for research, medical education and quality assurance: the Registration Network Family Practices.

General practitioners (GPs) possess a wealth of information on the health of their patients. Hence, they are in a unique position to gather information for research, education or management. The chief goal of the Registration Network Family Practices is to establish a computerized database containing certain patient characteristics and all relevant health problems excluding minor, temporary illnesses. The database can be seen as a dynamic population sampling frame of chronic and/or severe morbidity, also including risk factors and psychosocial problems. The best way to make use of the Registration Network Family Practices is by researchers identifying and sampling patients with particular health problems. The database contained patient characteristics and problemlists of 61,887 persons, on September 1, 1995. At that time 214,389 health problems had been entered in the database. The database is increasingly being used as a source of information for studies by researchers and students. Researchers find the database a useful tool, but they have to keep in mind that data on the process of care are not directly available. Furthermore, there is a limit to the number of studies which can be performed in the network practices, due to time limitations and the burden on the doctors and patients.

Data Collection↗
PubMed1996

Smoking in Dutch pregnant women and birth weight.

In this study 796 ambulatory singular pregnant women were questioned about their smoking habits both before and during pregnancy (ambispective). Important covariates such as parity, blood pressure, maternal weight gain, salt- and alcohol consumption and length of gestation were taken into account. At the beginning of pregnancy 52% of the questioned women smoked; 36% smoked in the seventh/eighth month of pregnancy. A dose-response relationship was found between the number of cigarettes smoked per day and birth weight. For those pregnant women who still smoked after 7 months of pregnancy an average birth weight loss of 24 g was found per cigarette per day. Even after controlling for covariates, there still remains an independent influence of smoking on birth weight loss on the average of 19 g for each cigarette smoked per day.

Adult↗
PubMed1996

The diagnostic value of the measurement of the ankle-brachial systolic pressure index in primary health care.

We investigated the value of the ankle-brachial systolic pressure index (ABPI) as a test for the diagnosis of peripheral arterial occlusive disease (PAOD) in general practice. ABPI measurements on 231 legs of 117 subjects performed in three general practice centers (GPC) were compared with the diagnostic conclusions of a Vascular Laboratory. The optimum cutoff value for the ABPI, its accuracy and diagnostic value were estimated. In a subpopulation of 51 subjects for whom repeated measurements were available, we checked whether taking the mean of three consecutive ABPIs for test outcome would enhance diagnostic performance. Receiver Operating Characteristic analysis showed that overall performance of the GPC ABPI was good (area under the curve approximately 0.9). Performing repeated ABPI measurements was superior to performing a single measurement. The optimum cutoff value for the ABPI was 0.97, associated with a diagnostic odds ratio (OR) of 17 and an accuracy of 81%. In a somewhat more selected subpopulation, the optimum cutoff value was 0.92 (OR 70, accuracy 90%). On the basis of our results, we suggest the following rule of thumb: if the ABPI < 0.8 or if the mean of three ABPIs < 0.9, it is highly probable that PAOD is present (PV+ > or = 95%); if the ABPI > 1.1 or if the mean of three ABPIs > 1.0, PAOD can be ruled out (PV- > or = 99%). In conclusion, in primary health care, the ABPI measurement can be a useful supplementary test in ambiguous diagnostic situations with regard to PAOD.

Adult↗