Figure 2.

Serum phosphate enrollment criteria at baseline affects changes in serum phosphate levels in reference groups of included studies in a systematic review. Black circles represent studies with no baseline requirement for participants’ serum phosphate levels; black squares represent studies in which participants were required to have recent hyperphosphatemia; white circles represent studies in which participants were required to have persistent hyperphosphatemia at baseline; white squares represent studies in which participants were required to have persistent hyperphosphatemia and hyperphosphatemia on most recent monthly blood test.