Six studies fell in the 'low methodological quality' category, 32 in the 'moderate' category and 19 in the 'good quality' category.
The methodological quality of each article was classified according to three categories (strong, moderate, or weak) based on six aspects: selection bias, study design, confounders, blinding, data collection, and withdrawals and dropouts.
Using univariate and not time-dependent analysis, the h-I was also associated with methodological quality either using scores (Table 4) or positive predictive value categories (Figure 1), randomization design, and with authors with several articles included (Table 5).
The methodological quality of the cohort studies was also evaluated in three categories.
For the other intervention categories the evidence was limited due to low methodological quality and the statistically insignificant results of the studies.
The guidelines for assessing and improving the methodological quality of economic evaluations in newborn screening are organized into 11 categories: "bibliographic details", "study question and design", "modelling", "health outcomes", "costs", "discounting", "presentation of results", "sensitivity analyses", "discussion", "conclusions", and "commentary".
We evaluated manuscript category of the included articles, and no further assessment of methodological quality was made.
The methodological quality of the included SRs was assessed with the validated Methodological Quality of Systematic Reviews (AMSTAR 55 instrument.
The methodological quality of the 23 systematic reviews in this overview, assessed using the Methodological Quality of Systematic Reviews Instrument, was found to be satisfactory.
Methodological quality of included studies varied considerably.
