The reporting quality of SRs has improved 3 y after publication of SR reporting st and ards , but the reporting of nutrition variables has not .
Improved adherence to consensus methods and reporting st and ards should improve the utility of nutrition SRs
BACKGROUND The quality of nutrition-related systematic review s ( SRs ) is an unstudied but important factor affecting their usefulness .
OBJECTIVES The objectives were to evaluate the reporting quality of published SRs and to identify areas of improvement .
Selenium supplementation and lung cancer incidence: an update of the nutritional prevention of cancer trial.
Interest in the chemopreventive effects of the trace element selenium has spanned the past three decades . Of > 100 studies that have investigated the effects of selenium in carcinogen-exposed animals , two-thirds have observed a reduction in tumor incidence and /or preneoplastic endpoints ( G. F. Combs and S. B. Combs , The Role of Selenium in Nutrition Chapter 10 , pp . 413 - 462 . San Diego , CA : Academic Press , 1986 , and B. H. Patterson and O. A. Lev and er , Cancer Epidemiol . Biomark . Prev . , 6 : 63 - 69 , 1997 ) . The Nutritional Prevention of Cancer Trial , a r and omized clinical trial reported by Clark et al. ( L. C. Clark et al. , JAMA , 276 : 1957 - 1963 , 1996 ) , showed as a secondary end point , a statistically significant decrease in lung cancer incidence with selenium supplementation . The adjusted hazard ratio ( HR ) was 0.56 [ 95 % confidence interval ( CI ) , 0.31 - 1.01 ; P = 0.05 ] . These results were based on active follow-up of 1312 participants . This re analysis used an extended Nutritional Prevention of Cancer Trial participant follow-up through the end of the blinded clinical trial on February 1 , 1996 . The additional 3 years added 8 cases to the selenium-treated group and 4 cases to the placebo group , and increased follow-up to 7.9 years . The relative risk of 0.70 ( 95 % CI , 0.40 - 1.21 ; P = 0.18 ) is not statistically significant . Whereas the overall adjusted HR is not significant ( HR = 0.74 ; 95 % CI , 0.44 - 1.24 ; P = 0.26 ) , and the HR for current and former smokers was not significant , the trend is toward a reduction in risk of incident lung cancer with selenium supplementation . In a subgroup analysis there was a nominally significant HR among subjects with baseline plasma selenium in the lowest tertile ( HR = 0.42 ; 95 % CI , 0.18 - 0.96 ; P = 0.04 ) . The analysis for the middle and highest tertiles of baseline showed HRs of 0.91 and 1.25 . The current re analysis indicates that selenium supplementation did not significantly decrease lung cancer incidence in the full population , but a significant decrease among individuals with low baseline selenium concentrations was observed
The reporting quality of SRs has improved 3 y after publication of SR reporting st and ards , but the reporting of nutrition variables has not .
Improved adherence to consensus methods and reporting st and ards should improve the utility of nutrition SRs
BACKGROUND The quality of nutrition-related systematic review s ( SRs ) is an unstudied but important factor affecting their usefulness .
OBJECTIVES The objectives were to evaluate the reporting quality of published SRs and to identify areas of improvement .