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ABSTRACT: BACKGROUND: To determine the diagnostic accuracy of a rapid heart-type fatty acid-binding protein (H-FABP) test in patients suspected of acute coronary syndrome (ACS) in primary care. METHODS: General practitioners included 298 patients suspected of ACS. In all patients, whether referred to hospital or not, ECG and cardiac biomarker testing was performed. ACS was determined in accordance with international guidelines. Multivariate analysis was used to determine the value of H-FABP in addition to clinical findings. RESULTS: Mean patient age was 66years (SD 14), 52% was female and 66 patients (22%) were diagnosed with ACS. The H-FABP bedside test was performed within 24h (median 3.1, IQR 1.5 to 7.1) after symptom onset. The positive predictive value (PPV) of H-FABP was 65% (95% confidence interval (CI) 50-78). The negative predictive value (NPV) was 85% (95% CI 80-88). Sensitivity was 39% (29-51%) and specificity 94% (90-96%). Within 6h after symptom onset, the PPV was 72% (55-84) and the NPV was 83% (77-88), sensitivity 43% (31-57%) and specificity 94% (89-97%). Adding the H-FABP test to a diagnostic model for ACS led to an increase in the area under the receiver operating curve from 0.66 (95% CI 0.58-0.73) to 0.75 (95% CI 0.68-0.82). CONCLUSION: The H-FABP rapid test provides modest additional diagnostic certainty in primary care. It cannot be used to safely exclude rule out ACS. The test can only be used safely in patients otherwise NOT referred to hospital by the GP, as an extra precaution not to miss ACS ('rule in').
International journal of cardiology 01/2013; · 7.08 Impact Factor
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ABSTRACT: - Important non-experimental study designs to assess the relation between a possible determinant (e.g. a treatment, a risk factor, a diagnostic or prognostic marker) and a clinical outcome are the follow-up and the case-control study design.- In case-control studies, the distribution of the determinant among subjects with the outcome (the 'cases') is compared to the distribution of this determinant in the underlying population from which the patients originate. This is typically estimated in a sample (the 'controls') of that population.- The main reason to consider a case-control design instead of a follow-up design is efficiency. A case-control study can be conducted faster and for lower costs, since only the cases and controls need to be studied in detail.- We illustrate the case-control study design by an example study into the relation between mobile phone use and the risk of traffic accidents, with a focus on the selection of controls.
Nederlands tijdschrift voor geneeskunde 01/2013; 157(11):A5697.
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ABSTRACT: The aim of this study was to assess the prevalence of (unknown) heart failure and left ventricular dysfunction in older patients with type 2 diabetes.
In total, 605 patients aged 60 years or over with type 2 diabetes in the south west of the Netherlands participated in this cross-sectional study (response rate 48.7%), including 24 with a cardiologist-confirmed diagnosis of heart failure. Between February 2009 and March 2010, the patients without known heart failure underwent a standardised diagnostic work-up, including medical history, physical examination, ECG and echocardiography. An expert panel used the criteria of the European Society of Cardiology to diagnose heart failure.
Of the 581 patients studied, 161 (27.7%; 95% CI 24.1%, 31.4%) were found to have previously unknown heart failure: 28 (4.8%; 95% CI 3.1%, 6.6%) with reduced ejection fraction, and 133 (22.9%; 95% CI 19.5%, 26.3%) with preserved ejection fraction. The prevalence of heart failure increased steeply with age. Heart failure with preserved ejection fraction was more common in women. Left ventricular dysfunction was diagnosed in 150 patients (25.8%; 95% CI 22.3%, 29.4%); 146 (25.1%; 95% CI 21.6%, 28.7%) had diastolic dysfunction.
This is the first epidemiological study that provides exact prevalence estimates of (previously unknown) heart failure and left ventricular dysfunction in a representative sample of patients with type 2 diabetes. Previously unknown heart failure and left ventricular dysfunction are highly prevalent. Physicians should pay special attention to 'unmasking' these patients.
Diabetologia 05/2012; 55(8):2154-62. · 6.81 Impact Factor
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ABSTRACT: Inleiding Er is weinig bekend over het praktische nut van elektrocardiografie in de huisartspraktijk. We onderzochten of elektrocardiografie
(ECG) in de huisartspraktijk leidt tot beleidsveranderingen.
Methode In een prospectief onderzoek in een groepspraktijk met acht huisartsen werden gedurende twee jaar alle gemaakte ECG's bestudeerd.
Om de indicatie voor het ECG en het geanticipeerde beleid vast te stellen vulden de aanvragende huisartsen twee vragenlijsten
in; een vóór en een na het vervaardigen van het ECG. De ECG's werden beoordeeld door één huisarts in de groepspraktijk met
ervaring in ECG-beoordeling en later ook door een cardioloog. Zestig willekeurige
Om de prognose van de patiënt te bepalen werd alle klinische informatie, verkregen gedurende zes maanden follow-up beoordeeld
door zowel de cardioloog als de huisarts.
Resultaten In totaal werden 301 ECG's bestudeerd, waarbij pijn op de borst (57%) en collaps/palpitaties (30%) de belangrijkste indicaties
waren. De overeenkomst in ECG-interpretatie tussen de beoordelende huisarts, cardioloog en de externe huisarts was goed (kappa
respectievelijk 0,70 en 0,64). Bij 92 patiënten (30,6%; 95%-BI: 25,4-35,8) veranderde het beleid van de aanvragende huisarts
naar aanleiding van de ECG-uitslag. De meest voorkomende veranderingen waren: niet verwijzen naar een cardioloog, terwijl
dit de bedoeling was voorafgaande aan het ECG (34%); verwijzen terwijl het de bedoeling was om dit niet te doen (20%) en verandering
in de cardiovasculaire medicatie (40%). Bij patiënten met pijn op de borst differentieert een (sterk) afwijkend ECG (aannemelijkheidquotiënt
(AQ): 13,3; 95%-BI: 6,9-25,5) en een normaal ECG (AQ: 0,06; 95%-BI: 0,7-1,1) erg goed tussen patiënten die wel of niet een
verhoogd risico hebben op een cardiovasculaire gebeurtenis in de nabije toekomst.
Conclusie Elektrocardiografie kan, in aanvulling op anamnese en lichamelijk onderzoek, een belangrijk hulpmiddel zijn in de huisartspraktijk.
diagnostiek-elektrocardiografie-hart- en vaatziekten-hartinfarct-hartritmestoornis
Huisarts en wetenschap 04/2012; 44(11):179-183.
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A J ten Cate-Hoek,
E F van der Velde,
D B Toll,
H C P M van Weert,
K G M Moons,
H R Büller, A W Hoes,
M A Joore,
R Oudega,
M H Prins,
H E J H Stoffers
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ABSTRACT: In patients initially suspected of deep venous thrombosis (DVT) the diagnosis can be confirmed in approximately 10 to 30% of cases. For the majority of patients this means that eventually an alternative diagnosis is assigned.
To assess the frequency distribution of alternative diagnoses and subsequent management of patients in primary care after initial exclusion of DVT. In addition, assess the value of ultrasound examination for the allocation of alternative diagnoses.
Data were recorded by general practitioners alongside a diagnostic study in primary care in the Netherlands (AMUSE). Additional data were retrieved from a three-month follow-up questionnaire. A descriptive analysis was performed using these combined data.
The most prevalent diagnoses were muscle rupture (18.5%), chronic venous insufficiency (CVI) (14.6%), erysipelas/cellulitis (12.6%) and superficial venous thrombosis (SVT) (10.9%). Alternative diagnoses were based mainly on physical examination; ultrasound examination (US) did not improve the diagnostic yield for the allocation of alternative diagnoses. In about 30% of all cases, a wait and see approach was used (27 to 41%). During the three-month follow-up nine patients were diagnosed with venous thromboembolic disease, three of which occurred in patients with the working diagnosis of SVT (p=0.026).
We found that after exclusion of DVT in general practice a wait and see policy in the primary care setting is uneventful for almost one third of patients, but with the alternative diagnosis of SVT, patients may require closer surveillance since we found a significant association with thrombosis in these patients.
The Netherlands Journal of Medicine 04/2012; 70(3):130-5. · 2.07 Impact Factor
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ABSTRACT: Detection of early chronic obstructive pulmonary disease (COPD) in patients presenting with respiratory symptoms is recommended; however, diagnosing COPD is difficult because a single gold standard is not available. The aim of this article is to review and interpret the existing evidence, theories and consensus on the individual parts of the diagnostic work-up for COPD. Relevant articles are discussed under the subheadings: history taking, physical examination, spirometry and additional lung function assessment. Wheezing, cough, phlegm and breathlessness on exertion are suggestive signs for COPD. The diagnostic value of the physical examination is limited, except for auscultated pulmonary wheezing or reduced breath sounds, increasing the probability of COPD. Spirometric airflow obstruction after bronchodilation, defined as a lowered ratio of the forced volume in one second to the forced vital capacity (FEV1/FVC ratio), is a prerequisite, but can only confirm COPD in combination with suggestive symptoms. Different thresholds are being recommended to define low FEV1/FVC, including a fixed threshold, and one varying with gender and age; however, the way physicians interpret these thresholds in their assessment is not well known. Body plethysmography allows a more complete assessment of pulmonary function, providing results on the total lung capacity and the residual volume and is indicated when conventional spirometry results are inconclusive. Chest radiography has no diagnostic value for COPD but is useful to exclude alternative diagnoses such as heart failure or lung cancer. Extensive history taking is of key importance in diagnosing COPD.
The Netherlands Journal of Medicine 01/2012; 70(1):6-11. · 2.07 Impact Factor
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ABSTRACT: BACKGROUND: Diagnosing acute coronary syndrome (ACS) in a primary care setting poses a diagnostic dilemma for physicians. OBJECTIVE: We directly compared the diagnostic accuracy of a clinical decision rule (CDR) based on history taking and physical examination in suspected ACS with the risk estimates of the attending GP. METHODS: In a prospective multicenter study, patients suspected of ACS were included by the GP. GPs were asked to estimate the probability (0%-100%) of the presence of ACS. GPs collected patient data, but they were not aware of the CDR and did not score the patient accordingly. RESULTS: Two hundred and ninety-eight patients were included (52% female, mean age 66 years, 22% ACS). The area under the receiver operating characteristic (ROC) curve (AUC) was 0.75 [95% confidence interval (CI) 0.68-0.82] for the GP risk estimate and 0.66 (95% CI 0.58-0.73) for the CDR. There was an agreement between the risk estimation of the GP and a CDR in 51% and the prevalence of ACS in predefined low-, intermediate- and high-risk groups was similar for the GP and CDR estimates. In the low-risk group, according to the GP, four patients (8.2%) suffered an ACS. These four patients were all identified by the decision rule as high risk. CONCLUSIONS: The GP classified patients as ACS or no ACS more adequately than the CDR, judged by the AUC. However, the use of a CDR in patients that are considered at low risk for ACS by the GP could reduce the amount of missed myocardial infarctions
Fam.Pract. 06/2011; 28(3).
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ABSTRACT: Diagnosing acute coronary syndrome (ACS) in a primary care setting poses a diagnostic dilemma for physicians.
We directly compared the diagnostic accuracy of a clinical decision rule (CDR) based on history taking and physical examination in suspected ACS with the risk estimates of the attending GP.
In a prospective multicenter study, patients suspected of ACS were included by the GP. GPs were asked to estimate the probability (0%-100%) of the presence of ACS. GPs collected patient data, but they were not aware of the CDR and did not score the patient accordingly.
Two hundred and ninety-eight patients were included (52% female, mean age 66 years, 22% ACS). The area under the receiver operating characteristic (ROC) curve (AUC) was 0.75 [95% confidence interval (CI) 0.68-0.82] for the GP risk estimate and 0.66 (95% CI 0.58-0.73) for the CDR. There was an agreement between the risk estimation of the GP and a CDR in 51% and the prevalence of ACS in predefined low-, intermediate- and high-risk groups was similar for the GP and CDR estimates. In the low-risk group, according to the GP, four patients (8.2%) suffered an ACS. These four patients were all identified by the decision rule as high risk.
The GP classified patients as ACS or no ACS more adequately than the CDR, judged by the AUC. However, the use of a CDR in patients that are considered at low risk for ACS by the GP could reduce the amount of missed myocardial infarctions.
Family Practice 01/2011; 28(3):323-8. · 1.50 Impact Factor
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ABSTRACT: Hospitalization for heart failure (HF) is associated with high-in-hospital and short- and long-term post discharge mortality. Age and gender are important predictors of mortality in hospitalized HF patients. However, studies assessing short- and long-term risk of death stratified by age and gender are scarce.
A nationwide cohort was identified (ICD-9 codes 402, 428) and followed through linkage of national registries. The crude 28-day, 1-year and 5-year mortality was computed by age and gender. Cox regression models were used for each period to study sex differences adjusting for potential confounders (age and comorbidities).
14,529 men, mean age 74 ± 11 years and 14,524 women, mean age 78 ± 11 years were identified. Mortality risk after admission for HF increased with age and the risk of death was higher among men than women. Hazard ratio's (men versus women and adjusted for age and co-morbidity) were 1.21 (95%CI 1.14 to 1.28), 1.26 (95% CI 1.21 to 1.31), and 1.28 (95%CI 1.24 to 1.31) for 28 days, 1 year and 5 years mortality, respectively.
This study clearly shows age- and gender differences in short- and long-term risk of death after first hospitalization for HF with men having higher short- and long-term risk of death than women. As our study population includes both men and women from all ages, the estimates we provide maybe a good reflection of 'daily practice' risk of death and therefore be valuable for clinicians and policymakers.
BMC Public Health 10/2010; 10:637. · 2.00 Impact Factor
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ABSTRACT: Guidelines for cardiovascular disease prevention recommend a non-pharmacological approach to reduce cardiovascular risk in those with elevated blood pressure. We assessed guideline adherence in hypertensives. This study was performed in the European Investigation into Cancer and Nutrition-NL cohort, consisting of 40,011 subjects. From 1993 to 1997, participants completed questionnaires (disease history, lifestyle and diet), a physical examination was performed and blood samples were drawn. Differences in proportions of guideline targets met between aware and unaware hypertensives were studied. Of 8779 hypertensive subjects, 90% was aware of their hypertension. They more often adhered to guidelines than unaware hypertensive subjects with respect to intake of polyunsaturated fat:saturated fat (38.6% vs 33.2%), fibres (40.6% vs 34.2%), body mass index <27 kg m(-2) (53.8% vs 46.5%) and alcohol (79.7% vs 72.6%). Despite statistical significance, the magnitude of these differences was small. Our study suggests that prevalence of a healthy lifestyle according to the recommendations in guidelines is slightly better in subjects aware of hypertension. There seems to be ample room for improvement in implementing the guidelines. Probably, patient tailored interventions and a multisiciplinary and multimodality approach can support this improvement.
Journal of human hypertension 09/2010; 24(9):561-7. · 2.80 Impact Factor
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Kristel J M Janssen,
Eit F van der Velde,
Arina J Ten Cate,
Martin H Prins,
Henk C P M van Weert,
H E Jelle H Stoffers,
Harry R Büller,
Ruud Oudega, Arno W Hoes,
Diane B Toll,
Karel G M Moons
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ABSTRACT: Recently, a diagnostic score was developed to safely exclude deep-vein thrombosis (DVT) in primary care. A large prospective study, in which general practitioners used this diagnostic score to decide which patients needed referral, revealed that the number of referrals for ultrasound measurements was reduced by almost 50%, at the cost of an acceptably low risk (1.4%, 95% confidence interval [CI] 0.6% to 2.9%) of venous thromboembolic events in non-referred patients. However, simple adjustments to the diagnostic score (so-called updating) might further improve the accuracy; i.e. reduce the proportion of missed diagnoses (safety) or increase the proportion of patients who do not need to be referred (efficiency). We applied two updating methods to determine whether adjusting the weights of the predictors or adding new predictors could further improve the accuracy of the diagnostic score. The weights of the predictors did not need to be adjusted, but inclusion of 'history of DVT' and 'prolonged travelling' significantly added predictive value (p-values 0.014 and 0.023, respectively). However, adding these predictors to the diagnostic score did not improve the safety and efficiency: at equal safety (1.4% missed diagnoses among the non-referred patients), the efficiency was lower (43.5%, 95% CI 40.4% to 46.6% compared to 49.4%, 95% CI 46.3% to 52.5%). The diagnostic score for excluding DVT in primary care has good accuracy in its original form and could not be improved by including additional predictors. This suggests that the original diagnostic score can be used to safely exclude clinically suspected DVT in primary care.
Thrombosis and Haemostasis 09/2010; 105(1):154-60. · 5.04 Impact Factor
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Archives of Internal Medicine - ARCH INTERN MED. 01/2010; 170(10):880-887.
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A.J. ten Cate-Hoek,
D.B. Toll,
H R Buller, A.W. Hoes,
K.G.M. Moons,
R. Oudega,
H E Stoffers,
E.F. van der Velde,
H.C. van Weert,
M H Prins,
M.A. Joore
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ABSTRACT: Referral for ultrasound testing in all patients suspected of DVT is inefficient, because 80-90% have no DVT. Objective: To assess the incremental cost-effectiveness of a diagnostic strategy to select patients at first presentation in primary care based on a point of care D-dimer test combined with a clinical decision rule (AMUSE strategy), compared with hospital-based strategies.
A Markov-type cost-effectiveness model with a societal perspective and a 5-year time horizon was used to compare the AMUSE strategy with hospital-based strategies. Data were derived from the AMUSE study (2005-2007), the literature, and a direct survey of costs (2005-2007).
Adherence to the AMUSE strategy on average results in savings of euro138 ($185) per patient at the expense of a very small health loss (0.002 QALYs) compared with the best hospital strategy. The iCER is euro55 753($74 848). The cost-effectiveness acceptability curves show that the AMUSE strategy has the highest probability of being cost-effective.
Results are sensitive to decreases in sensitivity of the diagnostic strategy, but are not sensitive to increase in age (range 30-80), the costs for health states, and events.
A diagnostic management strategy based on a clinical decision rule and a point of care D-dimer assay to exclude DVT in primary care is not only safe, but also cost-effective as compared with hospital-based strategies.
Journal of Thrombosis and Haemostasis 09/2009; · 5.73 Impact Factor
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ABSTRACT: The climacteric is accompanied by many changes in life, which may give cause to a variety of complaints. Thus, it may be difficult to discern to what extent the climacteric is related to well-being. The association between menopausal status and well-being was determined in a population of 2729 women aged 45-60 years. A self-administered questionnaire was filled out and returned by 1947 women (response 71.3%). Well-being was measured by the Inventory of Subjective Health (ISH) and the three subscales of the Sickness Impact Profile (SIP): social functioning; emotions, feelings and sensations; and intellectual functioning. The relationship between menopausal status and well-being was estimated using linear regression analysis, while adjusting for age and other potential confounding variables, including body mass index, smoking behavior, education, work outside the home, parity, way of cohabitation, difference in age with the partner and partner's employment. The results show that early perimenopausal women report a lower level of well-being as compared to premenopausal women on all three SIP scales. Early postmenopausal women report a lower level of well-being on the SIP emotions, feelings and sensations. Intermediate postmenopausal women have a lower level of well-being on the ISH only. Finally, late postmenopausal women have a lower level of well-being on the SIP social functioning and SIP emotions, feelings and sensations. We tentatively conclude that the influence of the climacteric on well-being independent of confounders is primarily found in behavioral functioning in the daily life of a woman.
07/2009; 14(2):127-143.
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ABSTRACT: To review the evidence on the diagnostic accuracy of the currently available point of care D-dimer tests for excluding venous thromboembolism.
Systematic review of research on the accuracy of point of care D-dimer tests, using bivariate regression to examine sources of variation and to estimate sensitivity and specificity.
Studies on the diagnostic accuracy of point of care D-dimer tests published between January 1995 and September 2008 and available in either Medline or Embase. Review methods The analysis included studies that compared point of care D-dimer tests with predefined reference criteria for venous thromboembolism, enrolled consecutive outpatients, and allowed for construction of a 2x2 table.
23 studies (total number of patients 13 959, range in mean age 38-65 years, range of venous thromboembolism prevalence 4-51%) were included in the meta-analysis. The studies reported two qualitative point of care D-dimer tests (SimpliRED D-dimer (n=12) and Clearview Simplify D-dimer (n=7)) and two quantitative point of care D-dimer tests (Cardiac D-dimer (n=4) and Triage D-dimer (n=2)). Overall sensitivity ranged from 0.85 (95% confidence interval 0.78 to 0.90) to 0.96 (0.91 to 0.98) and overall specificity from 0.48 (0.33 to 0.62) to 0.74 (0.69 to 0.78). The two quantitative tests Cardiac D-dimer and Triage D-dimer scored most favourably.
In outpatients suspected of venous thromboembolism, point of care D-dimer tests can contribute important information and guide patient management, notably in low risk patients (that is, those patients with a low score on a clinical decision rule).
BMJ (Clinical research ed.). 02/2009; 339:b2990.
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ABSTRACT: To determine the effectiveness of increasing the dietary content of soluble fibre (psyllium) or insoluble fibre (bran) in patients with irritable bowel syndrome.
Randomised controlled trial.
General practice.
275 patients aged 18-65 years with irritable bowel syndrome.
12 weeks of treatment with 10 g psyllium (n=85), 10 g bran (n=97), or 10 g placebo (rice flour) (n=93).
The primary end point was adequate symptom relief during at least two weeks in the previous month, analysed after one, two, and three months of treatment to assess both short term and sustained effectiveness. Secondary end points included irritable bowel syndrome symptom severity score, severity of abdominal pain, and irritable bowel syndrome quality of life scale.
The proportion of responders was significantly greater in the psyllium group than in the placebo group during the first month (57% v 35%; relative risk 1.60, 95% confidence interval 1.13 to 2.26) and the second month of treatment (59% v 41%; 1.44, 1.02 to 2.06). Bran was more effective than placebo during the third month of treatment only (57% v 32%; 1.70, 1.12 to 2.57), but this was not statistically significant in the worst case analysis (1.45, 0.97 to 2.16). After three months of treatment, symptom severity in the psyllium group was reduced by 90 points, compared with 49 points in the placebo group (P=0.03) and 58 points in the bran group (P=0.61 versus placebo). No differences were found with respect to quality of life. Fifty four (64%) of the patients allocated to psyllium, 54 (56%) in the bran group, and 56 (60%) in the placebo group completed the three month treatment period. Early dropout was most common in the bran group; the main reason was that the symptoms of irritable bowel syndrome worsened.
Psyllium offers benefits in patients with irritable bowel syndrome in primary care.
Clinical trials NCT00189033.
BMJ (Clinical research ed.). 02/2009; 339:b3154.
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ABSTRACT: The validity of non-randomized studies using healthcare databases is often challenged because they lack information on potentially important confounders, such as functional health status and socioeconomic status. In a study quantifying the effects of influenza vaccination among community-dwelling elderly we assessed whether additional information on not routinely available covariates was indeed associated with exposure to influenza vaccination and could, therefore, have led to residual confounding in healthcare databases.
We randomly selected 500 persons aged 65 years and older from the computerized Utrecht General Practitioner database. Information on exposure status and on demographics, co-morbidity status, prior healthcare use and medication use was extracted from the database. A questionnaire was used to obtain additional information on not routinely available risk factors [e.g. functional health status (SF-20), smoking status and alcohol consumption]. Missing data from the questionnaire was imputed and multivariable logistic regression analysis was applied to quantify the influence of covariates on the prediction of exposure to influenza vaccination. Within an existing dataset the potential impact of functional health status on the relation between influenza vaccination and mortality was simulated.
We obtained questionnaire data from 365 of 500 (73%) subjects. The model including routinely available data from the database appeared accurate in predicting exposure to influenza vaccination (c-statistic 0.86, 95% CI: 0.82-0.89). Functional health status was the only additional characteristic measured with the questionnaire that was not similar in vaccinated and unvaccinated subjects. However, extending the multivariable regression model with functional health status did not significantly improve the prediction of exposure to influenza vaccination, nor did it affect the relation between influenza vaccination and mortality.
The potential for unmeasured confounding on the association between influenza vaccination and health outcomes as quantified in healthcare databases seems small for non-randomized intervention studies within extensive and reliable databases.
International Journal of Epidemiology 09/2008; 37(6):1422-9. · 6.41 Impact Factor
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ABSTRACT: The recruitment process may generate a selected patient sample, which may threaten the generalizability of trial results. This risk is particularly high in case disease and patient characteristics demonstrate a wide variation, such as in irritable bowel syndrome (IBS). We compared IBS patients who were selected, approached, and randomized to participate in a clinical trial assessing the efficacy of dietary fiber therapy in IBS.
Retrospective survey in primary care patients diagnosed with IBS by their general practitioner in the past 2 years selected and invited for participation in a trial. Characteristics were compared between randomized patients (n=193) nonrandomized eligible patients (n=371), and patients not eligible for participating in the trial (n=724).
Of the 2,100 IBS patients, 1,288 (61%) returned the questionnaire. Randomized patients had a higher intensity of IBS abdominal pain as compared to the other groups, a higher consultation rate and a longer IBS disease history. Noneligible patients had less active IBS symptoms.
Patients randomized do differ from those nonrandomized in IBS disease characteristics. These observations may have implications for the applicability of our research outcome.
Journal of clinical epidemiology 08/2008; 61(11):1176-81. · 2.96 Impact Factor
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ABSTRACT: In nonrandomized intervention studies unequal distribution of patient characteristics in the groups under study may hinder comparability of prognosis and therefore lead to confounding bias. Our objective was to review methods to control for observed confounding, as well as unobserved confounding
We reviewed epidemiologic literature on methods to control for observed and unobserved confounding.
Various methods are available to control for observed (i.e., measured) confounders, either in the design of data collection (i.e., matching, restriction), or in data analysis (i.e., multivariate analysis, propensity score analysis). Methods to quantify unobserved confounding can be categorized in methods with and without prior knowledge of the effect estimate. Without prior knowledge of the effect estimate, unobserved confounding can be quantified using different types of sensitivity analysis. When prior knowledge is available, the size of unobserved confounding can be estimated directly by comparison with prior knowledge.
Unobserved confounding should be addressed in a quantitative way to value the inferences of nonrandomized intervention studies.
Journal of clinical epidemiology 08/2008; 62(1):22-8. · 2.96 Impact Factor
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ABSTRACT: Recently, a new, simple diagnostic rule was introduced to enable GPs to safely refrain from referring a considerable proportion of the patients suspected of having deep vein thrombosis (DVT). The rule (which includes seven patient history and physical examination items plus the result of a D-dimer test) discriminates 'very low' risk patients (not to be referred) from patients with an increased risk of DVT (to be referred). However, the rule's 'efficiency' (proportion of patients designated by the rule as very low risk) and safety (DVT prevalence among these very low risk patients) may change according to patient characteristics.
To test the rule's safety and efficiency in clinically relevant subgroups; i.e. across three age groups, in men and women, and in patients with and without a history of DVT, separately.
We retrospectively analysed data of 2086 primary care patients suspected of DVT, in whom all rule items and the result of the reference ('gold') standard (compression ultrasonography) were collected.
The rule's efficiency decreased with age from 38.1% in the relatively young (<50 years) compared to 9.8% in patients aged > or =70 years. The percentage of DVT among the very low risk patients was <1.5% in all subgroups. The low efficiency in the elderly could be improved without compromising the safety by increasing the D-dimer threshold.
The rule can safely exclude DVT in primary care patients suspected of DVT, irrespective of age, gender and history of DVT.
Family Practice 03/2008; 25(1):3-8. · 1.50 Impact Factor
