This may be due to the specific difficulties that

apply to meta-analyses of observational research. The aim of this paper is to provide a nontechnical overview of the principles of meta-analysis applied to observational research. We will highlight general principles of meta-analysis and discuss the major threats to its validity, with an emphasis on its specific merits and pitfalls for psychosomatic research, using several examples. We conclude that meta-analysis is a relatively simple technique, leaving little reason for not routinely applying it when performing a systematic review. An adequately conducted meta-analysis may not only provide a summary estimate of a certain association, but it has additional value in discovering relevant confounders, mediators, and moderators, as well

as identifying areas of research that require more attention.”
“BACKGROUND

Magnetic CP673451 order AZD9291 chemical structure resonance imaging (MRI) is frequently performed during follow-up in patients with known lumbar-disk herniation and persistent symptoms of sciatica. The association between findings on MRI and clinical outcome is controversial.

METHODS

We studied 283 patients in a randomized trial comparing surgery and prolonged conservative care for sciatica and lumbar-disk herniation. Patients underwent MRI at baseline and after 1 year. We used a 4-point scale to assess disk herniation on MRI, ranging from 1 for “”definitely present”" to 4 for “”definitely absent.”" A favorable clinical outcome was defined as complete

or nearly complete disappearance of symptoms at 1 year. We compared proportions of patients with a favorable outcome among those with a definite https://www.selleck.cn/products/beta-nicotinamide-mononucleotide.html absence of disk herniation and those with a definite, probable, or possible presence of disk herniation at 1 year. The area under the receiver-operating-characteristic (ROC) curve was used to assess the prognostic accuracy of the 4-point scores regarding a favorable or unfavorable outcome, with 1 indicating perfect discriminatory value and 0.5 or less indicating no discriminatory value.

RESULTS

At 1 year, 84% of the patients reported having a favorable outcome. Disk herniation was visible in 35% with a favorable outcome and in 33% with an unfavorable outcome (P = 0.70). A favorable outcome was reported in 85% of patients with disk herniation and 83% without disk herniation (P = 0.70). MRI assessment of disk herniation did not distinguish between patients with a favorable outcome and those with an unfavorable outcome (area under ROC curve, 0.48).

CONCLUSIONS

MRI performed at 1-year follow-up in patients who had been treated for sciatica and lumbar-disk herniation did not distinguish between those with a favorable outcome and those with an unfavorable outcome. (Funded by the Netherlands Organization for Health Research and Development and the Hoelen Foundation; Controlled Clinical Trials number, ISRCTN26872154.