“…67,71,80,93,109,139,156 Valuation of costs: Only a few studies calculated the actual cost prices. 68,125,136 As is common in economic evaluation studies, charges were used as a proxy for the costs in many studies. 58-61, 70, 73, 74, 84, 86, 87,91, 98, 102, 106, 107, 111, 113, 116,128,135,138,140,142,150 Charges are not costs but rather 'negotiated prices'.…”