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A review of the literature suggests there are two major aspects of responsiveness. We define the first as "internal responsiveness," which characterizes the ability of a measure to change over a prespecified time frame, and the second as "external responsiveness, " which reflects the extent to which change in a measure relates to corresponding change in a(More)
The relative benefit of an active treatment over a control is usually expressed as the relative risk, the relative risk reduction, or the odds ratio. These measures are used extensively in both clinical and epidemiological investigations. For clinical decision making, however, it is more meaningful to use the measure "number needed to treat." This measure(More)
The cumulative sum (CUSUM) procedure is a graphical method that is widely used for quality monitoring in industrial settings. More recently it has been used to monitor surgical outcomes whereby it 'signals' if sufficient evidence has accumulated that there has been a change in the surgical failure rate. A limitation of the standard CUSUM procedure in this(More)
BACKGROUND Understanding the risk factors for ventilator-associated pneumonia can help to assess prognosis and devise and test preventive strategies. OBJECTIVE To examine the baseline and time-dependent risk factors for ventilator-associated pneumonia and to determine the conditional probability and cumulative risk over the duration of stay in the(More)
OBJECTIVE To analyze predictive factors for the development of osteonecrosis (ON) in a large cohort of patients with systemic lupus erythematosus (SLE) followed in a single center. METHODS A nested matched case control design was used. Patients with SLE who developed ON during followup were identified from the University of Toronto Lupus Clinic database.(More)
Chronic medical conditions are often manifested by the incidence of recurrent adverse clinical events. In clinical trials designed to investigate therapeutic interventions for such conditions it is natural to make treatment comparisons on the basis of event occurrence. However, when there is a more serious, possibly related, event that terminates the(More)
Events that may occur repeatedly for individual subjects are of interest in many medical studies. We review methods of analysis for repeated events, emphasizing that the approach taken in a given study should allow clinical questions to be addressed as directly as possible. Methods based on full models for event processes as well as on simpler 'marginal'(More)
Our objective was to compare the reliability and responsiveness of the original Steinbrocker's (OS), our modified Steinbrocker's (MS) and Larsen's (L) radiological scoring methods for detecting radiological change in psoriatic arthritis over time. Two sets of radiographs of the hands and feet at least 2 yr apart were selected from 68 patients. Films were(More)
OBJECTIVE To compare health-related quality of life (QOL) between patients with psoriatic arthritis (PsA) and patients with rheumatoid arthritis (RA), using the Medical Outcomes Study Short Form health survey (SF-36) and the Health Assessment Questionnaire (HAQ). METHODS Both the SF-36 and the HAQ were administered to 107 PsA patients attending the(More)