TABLE 2.

QUIPS Tool, Subjective Grading for Bias (High*, Moderate^†, Low^‡)

Reference	Study Participation	Study Attrition	Prognostic Factor Measurement	Outcome Measurement	Adjustment for Other Prognostic Factors	Statistical Analysis and Reporting
Abbai et al28	Moderate	Moderate	Low	Low	Moderate	Low
Balkus et al29	Moderate	High	Low	Low	High	Low
Balkus et al40	Low	Low	Low	Low	Moderate	Low
Brahmbhatt et al30	Low	Moderate	Low	Low	Moderate	Moderate
Brotman et al33	High	Moderate	Low	Low	Moderate	High
Brotman et al34	Low	Moderate	Low	Moderate	Moderate	Low
Fichorova et al38	Low	Moderate	Low	Low	Moderate	Moderate
Jarrett et al31	Moderate	Moderate	Low	Low	High	Moderate
Kapiga et al32	Moderate	Moderate	Low	Low	Moderate	Low
Kaul et al41	Low	Low	Low	Low	Moderate to High	Low
Kenyon et al35	Low	Moderate	Low	Moderate	Low	Low
Martin et al42	Moderate	Moderate	Moderate	Moderate	Low	Low
Nijhawan et al36	Low	Moderate	Low	Moderate	Moderate	Low
Rathod et al39	Moderate	Moderate	Low	Low	High	Moderate

*“High” risk: the relationship between the prognostic factor and the outcome is very likely to be different for the domain of interest.

^†“Moderate” risk: the relationship between the prognostic factor and the outcome may be different for the domain of interest.

^‡“Low” risk: the relationship between the prognostic factor and the outcome is very unlikely to be different for the domain of interest.