Errors in questionnaire surveys are usually of one of two sources: non-responses or incorrect answers. The aim was to investigate the validity of a questionnaire survey and to estimate the respective bias of these answers. Of 9,283 subjects selected to receive a questionnaire by post, 3,949 (43%) responded, and, of these, 3,400 correctly reported their Swedish social security number. Answers in the questionnaire survey were given as proportions of the claims registered at local insurance offices. In the group of respondents who had correctly reported their social security number, the answers were compared individually with the registrations in dental insurance claims. In Sweden, these claims are labeled with the patient's social security number and it is thereby possible to make such comparisons. It was shown that errors were caused by non-response and also by respondents giving incorrect answers. Incorrect answers accounted for approximately one-third of the total bias. The remaining bias was caused by a non-response error. It is concluded that questionnaire studies have a bias caused by both non-response and incorrect answers and that together these can be substantial. Scientific reports that include questionnaire surveys must describe the procedure carefully. If possible, other sources of information should be considered.
INTRODUCTION: Brugada syndrome (BrS) is an inherited disorder that predisposes some subjects to sudden cardiac death (SCD). It is not well established which BrS patients are at risk of severe arrhythmias. Our aim was to study whether standard 12-lead electrocardiogram (ECG) would give useful information for this purpose. METHODS: This study included 200 BrS probands (142 male, 62%; mean age 42 +/- 16 years). Symptoms related to BrS were defined as syncope, documented ventricular tachyarrhythmia, or SCD. We determined PR, QRS, QTc, T(peak), and T(end) interval from leads II and V(2) and QRS from lead V(5), R'/S ratio from lead aVR (aVR sign), QRS axis, and J-point elevation amplitude from right precordial leads from the baseline ECGs. RESULTS: Sixty-six subjects (33%) had experienced symptoms related to BrS. The only significant difference between the symptomatic and asymptomatic BrS subjects was the QRS duration measured from lead II or lead V(2), for example, the mean QRS in V(2) was 115 +/- 26 ms in symptomatic versus 104 +/- 19 ms in asymptomatic patients (P or =120 ms gave an odds ratio (OR) of 2.5 (95% CI: 1.4-4.6, P = 0.003) for being symptomatic. In a multivariate analysis adjusted with gender, age, and SCN5A mutation, the OR was 2.6 (95% CI: 1.4-4.8, P = 0.004). CONCLUSION: Prolonged QRS duration, measured from standard 12-lead ECG, is associated with symptoms and could serve as a simple noninvasive risk marker of vulnerability to life-threatening ventricular arrhythmias in BrS.
The 12-item version of the General Health Questionnaire (GHQ-12) is frequently used to measure common mental disorder in public health surveys, but few population-based validations have been made. We validated the GHQ-12 against structured psychiatric interviews of depression using a population-based cohort in Stockholm, Sweden.
We used a population-based cohort of 484 individuals in Stockholm, Sweden (participation rate 62%). All completed the GHQ-12 and a semi-structured psychiatric interview. Last month DSM-III-R symptoms were used to classify major and minor depression. Three scoring methods for GHQ-12 were assessed, the Standard, Likert and Corrected method. Discriminatory ability was assessed with area under the receiver operating characteristic (ROC) curve.
A total of 9.5% had a major or minor depression. The area under the ROC curve was for the Standard method 0.73 (0.65-0.82), the Likert method 0.80 (0.72-0.87) and the Corrected method 0.80 (0.73-0.87) when using major or minor depression as standard criterion. Adequate sensitivity and specificity for separating those with or without a depressive disorder was reached at =12 Likert scored points (80.4 and 69.6%) or =6 Corrected GHQ points (78.3 and 73.7%). Sensitivity and specificity was at =2 Standard scored points 67.4% and 74.2%.
When scored using the Likert and Corrected methods, the GHQ-12 performed excellently. When scored using the Standard method, performance was acceptable in detecting depressive disorder in the general population. The GHQ-12 appears to be a good proxy for depressive disorder when used in public health surveys.
The continuous change of the ST and QRS vectorcardiograms reflect the underlying ischemic event, and can be used as a tool in the management of the acute event. It also reflects reperfusion, and can guide the clinician on when and how to intervene. Continuous vectorcardiography has proven to add prognostic information, both in the acute phase (can be used already in the ambulance during transportation to CCU) and after discharge from hospital. This paper reviews the origin of continous vectorcardiography as a monitoring device in AMI, including the follow-up research until today.
The Canadian Quality Assurance Program was initiated in June 1989, and is a voluntary program which currently encompasses all 32 laboratories involved in the measurement of cyclosporine (CsA) across Canada. Two whole blood samples from control or clinical patients (kidney, liver and heart) containing unknown concentrations of CsA are circulated to each participating laboratory monthly, and analyzed by all techniques employed within that laboratory. Four analytical methods are currently employed: HPLC (n = 4). Sandimmun SP (n = 3), CycloTrac SP (n = 27) and TDx (n = 3). Four laboratories reported survey results in more than one methodology. Results from all participating centers are analyzed monthly. The mean, SD, standard deviation index and range are reported to each laboratory with information coded to preserve confidentiality. Accuracy, precision, recovery, analytical specificity, linearity and blank studies have been performed. This report covers the period from June 1989 to April 1990.