PubMed Health⌕ Search

Biomedical subjects

M N Lassere

Publications and source records attributed to M N Lassere.

8 recordsLinked to original sources
PubMed2002

Poor accuracy and interobserver reliability of knee arthroscopy measurements are improved by the use of variable angle elongated probes.

OBJECTIVES: (a)To determine the accuracy and reliability of arthroscopic measurements of cartilage lesion diameter in an artificial right knee model; (b) to determine whether the use of a set of variable angle elongated probes improves performance; and (c) to identify other sources of variability. METHODS: Ovoid "lesions" were drawn on the five cartilage surfaces of four plastic knees models. Two observers assessed these 20 lesions arthroscopically, measuring two diameters in orientations parallel and orthogonal to the probe. Observer 1 (orthopaedic surgeon) and observer 2 (arthroscopic rheumatologist) made two sets of measurements, firstly with the conventional probe and five months later with the variable angle elongated (VAE) probes. The knees were disarticulated to determine true lesion diameter. RESULTS: Observer 1 had negligible bias and good accuracy regardless of orientation or probe type. Observer 2 demonstrated both bias and poor accuracy using the conventional probe. Both improved using VAE probes. Poor interobserver reliability with conventional probes also improved using VAE probes. Major sources of variability could be traced to the probe type, the characteristics of the operator, and the orientation of the lesion in relation to the probe; the lesion location itself did not cause variability. CONCLUSIONS: Variation in accuracy and poor interobserver reliability of measurements with conventional methods of cartilage lesion diameter measurement improved when specially designed measurement probes were used. Arthroscopic measurements performed as well as most clinical and radiographic measures. These findings have important implications for the use of arthroscopy as an outcome in multicentre trials where arthroscopists have different levels of experience.

Analysis of Variance↗
PubMed2001

Foundations of the minimal clinically important difference for imaging.

This article develops a generic conceptual framework for defining and validating the concept of minimal clinically important difference. We propose 3 approaches. The first uses statistical descriptions of the population ("distribution based"), the second relies on experts ("opinion based"), and a third is based on sequential hypothesis formation and testing ("predictive/data driven based"). The first 2 approaches serve as proxies for the third, which is an experimentally driven approach, asking such questions as "What carries the least penalty?" or "What imparts the greatest gain?" As an experimental approach, it has the expected drawbacks, including the need for greater resources, and the need to tolerate trial and error en route, compared to the other 2 models.

Arthritis, Rheumatoid↗
PubMed2001

Reliability of measures of disease activity and disease damage in rheumatoid arthritis: implications for smallest detectable difference, minimal clinically important difference, and analysis of treatment effects in randomized controlled trials.

We evaluate measurement properties of common rheumatoid arthritis (RA) assessments. Included are a comprehensive literature review and new data on the reliability and smallest detectable difference (SDD) for different classes of these measures. We found that certain common measures such as joint counts, pain, and patient global all had poor reliability and showed large SDD compared to multi-item measures of physical/psychological function or compared to radiographic measures. We discuss the implications of these findings on the use of composite endpoints such as the ACR20 or the EULAR responder index in RA clinical trials, particularly the introduction of misclassification bias that arises from differential measurement error. Finally, we consider generically how the concept of the SDD might or might not relate to the concept of the minimal clinically important difference.

Aged↗
PubMed2001

Robustness and generalizability of smallest detectable difference in radiological progression.

The smallest detectable difference (SDD) reflects that component of a measure statistically attributable to error from the measurement process itself. As such it is an irreducible component of the inherent variability in measurements in clinical trials and will affect their design, whether randomized or observational. Even though the application of the SDD concept to assaying radiographs in rheumatoid arthritis is relatively new and not well understood, systematic work on the influences of radiographic SDD can be done. This report describes the effects of a number of clinical aspects of the disease and operational aspects of trials on the values of the SDD of radiographic progression data. We show that if conditions affecting SDD are known and kept constant across datasets, the SDD of radiological progression from one study may be generalizable to other studies. However, if any one condition varies, the SDD is distinctly unrobust and cannot be generalized to other studies.

Arthritis, Rheumatoid↗
PubMed2001

Measurements of rheumatoid arthritis disease activity and damage using magnetic resonance imaging. Truth and discrimination: does MRI make the grade?

Magnetic resonance imaging (MRI) is a tool with unprecedented capabilities. Rheumatoid arthritis (RA) abnormalities that can be measured with MRI include erosions, articular cartilage thickness, synovial membrane volume, and pannus. However, as access to MRI increases, there is a risk that its use will not be evaluated using rigorous scientific measurement principles. We reviewed published MRI measurement methods for RA and investigated whether the methods were systematically evaluated for reliability, validity, and responsiveness to change--components of the OMERACT filter. Medline and Embase databases were searched from 1966 to 1999. Titles and abstracts were scanned to identify publications on MRI methods used to assess either disease activity or damage in RA. A data extraction template was developed and 68 peer reviewed publications from 40 research groups were appraised; 40 addressed RA disease activity, 4 RA damage, and 24 both activity and damage. Joints most frequently assessed were knee (32 publications) and wrist (31 publications). Ninety-one percent of publications evaluated either reliability or validity or responsiveness to change. Thirteen percent evaluated all 3 and only 9% evaluated none of these measurement properties. Validity was evaluated in 85%, responsiveness to change in 37%, and reliability in 35% of publications. Only 12% of publications evaluated both intra and inter-reliability. Few publications of MRI measures of disease activity or damage in RA met the OMERACT filter for all measurement properties. It would be regrettable if MRI measures are developed ad hoc, with little regard to considerations of scaling, reliability, validity, and responsiveness to change, because this will severely limit their ability to confidently assess treatment efficacy and prognostic indicators.

Arthritis, Rheumatoid↗
PubMed1991

Driving and arthritis.

In a 3-year period, 94 patients with driving difficulties due to a variety of musculoskeletal disorders were assessed by the occupational therapy department of a rheumatology unit. The individual's ability to carry out each part of the driving process was recorded and the patients were classified into six broad categories. While some parts of the driving process often proved difficult, patterns of disability were found with different musculoskeletal disorders. Almost all of these difficulties could be overcome by simple modifications to vehicle or driving technique. Only one severely disabled individual required referral to a specialized mobility unit, while two individuals were found to be unsafe. Thus, almost all arthritic individuals are able to continue driving with the help of simple modifications. By providing an unsophisticated driving assessment service, a rheumatology unit can enable patients to continue driving and so maintain independence.

Arthritis↗
PubMed1990

Recurrent calcific periarthritis, erosive osteoarthritis and hypophosphatasia: a family study.

We describe a mother and 2 daughters with familial recurrent calcific periarthritis in a family with an inherited tendency to develop generalized osteoarthritis (OA). Low levels of serum alkaline phosphatase were found in 1 of the daughters while the mother developed erosive OA in later life. HLA typing was noncontributory. However, the 3 individuals with periarthritis possessed blood group A+, while the 6 unaffected family members were O+. The experience of this family adds weight to the case that recurrent calcific periarthritis may be due to an inherited abnormality of alkaline phosphatase production and suggest that this may also be responsible for the recently observed association of calcific periarthritis and erosive OA.

Adult↗