However these between center comparisons are indirect, and it is possible that differences in maternal characteristics, gestational age, and pregnancy factors (i.e. maternal nutrition, gestational diabetes, hypertension) may explain these differences.
The ISAAC questionnaire has been validated in terms of physician assessment (Jenkins et al. 1996), comparison between surveys of 6- to 7-year-olds and 13- to 14-year-olds carried out independently in the same center, comparisons with independent adult asthma surveys in the same country (Pearce et al. 2000), and comparisons with national hospital admission and mortality rates (Anderson et al. 2008).
Previous methods reporting percentages of HLA-DR positive cells (%HLA-DR) or mean fluorescence intensities (MFI) lacked an internationally accepted analytical standard and precluded between-center comparison of results [51].
Another four-center comparison was conducted among members of the Elispot standardization group of the ANRS in France [ 32].
Notwithstanding the limitations of a non-randomized single-center comparison, the results are in line with very preliminary data of randomized comparisons suggesting an improved outcome with ST.
The success of quantitative ultrasound for bone mineral density assessment should be attributed in part to its direct measurement of intrinsic physical parameters, including speed of sound and attenuation [ 18], which made cross-center comparison and instrumentation standardization possible.
A multi-center comparison of these assays demonstrated that while FD-DAT and rK39 tests are highly reliable in the Indian Subcontinent, >95% sensitivity and >90% specificity, they are less useful in Africa [ 9].
The EPHect SOPs allow endometriosis research centers to decrease variability in tissue-based results, facilitating between-center comparisons and collaborations.
The Endometriosis Phenome and Biobanking Harmonisation Project SOPs allow endometriosis research centers to decrease variability in biofluid sample results, facilitating between-center comparisons and collaborations.
Regular participation in multi-center comparisons could thereby help to optimize and validate participants' performance over time and to maintain sensitive protocols or minimal standards.
This assay has been carefully demonstrated to give reproducible results both within and between centers., Universal adoption of the reference center's assay method by BSV developers would greatly assist inter-center comparisons of vaccine candidates.
