Description of the included studies
| Author, year, country | Study design | Sampling time | Population | Intervention | Comparison | Outcomes |
| Farasatkish et al, 2009, Iran33 | Two-group after study | May 2007 through August 2007 | N=1716, open-heart surgery, ASA class III–IV | Pre-anaesthesia consultation clinic (3–10 days before surgery) | Usual care (within 24 hours of surgery) | Cancellations |
| Kamal et al, 2011, England34 | Two-group after study | April 2005 through April 2009 | N=1445, complex elective orthopaedic surgery, ASA class III–IV | Preoperative anaesthetic assessment clinic (timing not stated) | Usual care (day of surgery) | Admissions, length of stay, mortality, cost |
| Kamau et al, 2017, Kenya31 | CBA | August 2000, April 2001, November 2001 | N=51, elective non-cardiac surgery, ASA class not stated | Pre-anaesthesia clinic consultation (≥48 hours before surgery) | Usual care (day before surgery) | Anxiety (STAI score) |
| Klopfenstein et al, 2000, Switzerland30 | Two-group after study (parallel) | No data | N=40, elective endoscopic urological surgery, ASA class I–III | Pre-anaesthetic consultation (1–2 weeks before surgery) | Usual care (the evening before surgery) | Anxiety (MAACL, VAS) |
| Lee et al, 2012, China35 | Two-group after study (parallel) | March 2007 through November 2009 | N=352, elective surgery, ASA class I–IV | Anaesthesia consultation clinic (≤3 months before surgery) | Usual care (the evening before surgery) | Quality of recovery score, cost, cancellations, length of stay, satisfaction, anxiety (VAS), willingness to pay |
| Mendes et al, 2005, Brazil36 | Two-group after study (parallel) | April 2007 through June 2007 | N=52 254, surgery, ASA class not stated | Preoperative outpatient evaluation clinic (timing not stated) | Usual care (timing not stated) | Cancellations, length of stay, PAC evaluations, outpatient procedures |
| van Klei et al, 2002, The Netherlands32 | Two-group after study | November 2012 | N=21 553, elective surgery, ASA class not stated | Preoperative outpatient evaluation clinic (average 3 weeks before surgery) | Usual care (day before surgery) | Cancellations |
ASA, American Society of Anesthesiologists; CBA, controlled before–after; MAACL, Multiple Affect Adjective Check List; PAC, Preanesthetic assessment clinic; STAI, State-Trait Anxiety Inventory; VAS, Visual Analogue Scale.