title: A randomised clinical trial of routine versus selective CT imaging in acute abdomen: Impact of patient age on treatment costs and hospital resource use.
abstract: OBJECTIVE
  To evaluate the impact of patient age on hospital resource use and treatment costs of acute abdominal pain (AAP).
  
  
  METHODS
  A total of 300 adult patients with AAP were randomised to either computed tomography (CT, n=150) or selective imaging practice (SIP, n=150) groups. Final analysis included 254 patients, 143 (42 patients ≥65years) in the CT and 111 (32 patients ≥65years) in the SIP group. All CT group patients underwent abdominal CT whereas in the SIP group, imaging was based on the clinical assessment. For each patient, the hospital length of stay (LOS), the numbers and costs of diagnostic and treatment procedures arising from AAP were calculated and registered. The incremental cost-effectiveness ratio (ICER) and bootstrapped cost-effectiveness acceptability curve (CEAC) were estimated for routine CT.
  
  
  RESULTS
  Treatment costs, imaging costs and LOS increased in conjunction with aging in both study groups, and were generally higher in the CT group compared to the SIP group. In the SIP group, CT was undertaken in 34% (27/79) of the <65year olds but in 59% (19/32) of the older patients (≥65years) (p=0.02). The proportion of patients with non-specific abdominal pain was significantly lower in patients ≥65years than in their younger counterparts (p=0.04). In the routine CT group, the ICER of obtaining a specific diagnosis was 1682 € for patients <65years and 1055 € for patients ≥65years. According to CEAC estimation, routine CT for every patient with AAP has a 95% probability of being cost-effective if society is willing to pay 14087 € for an additional specific diagnosis for patients <65 years but only 4204 € in those ≥65years.
  
  
  CONCLUSIONS
  Treatment costs of AAP increase in parallel with aging, and the costs are generally higher with routine CT compared to selective imaging. The probability of obtaining a specific diagnosis of AAP increases with aging. If obtaining a specific diagnosis is deemed crucial, then routine CT is more cost-effective in patients over 65 years compared to younger patients. Considering the diagnostic challenges of AAP in the elderly, liberal CT use can be advocated in this patient group.
authors.affiliation: Department of Clinical Radiology, Kuopio University Hospital, Puijonlaaksontie 2, FI-70210, Kuopio, Finland. Electronic address: tiina.lehtimaki@kuh.fi.
authors.forename: Tiina T
authors.initials: TT
authors.lastname: Lehtimäki
authors.affiliation: University of Eastern Finland, Department of Health and Social Management, Yliopistonranta 1, FI-70211 Kuopio, Finland. Electronic address: hannu.valtonen@uef.fi.
authors.forename: Hannu
authors.initials: H
authors.lastname: Valtonen
authors.affiliation: Department of Gastrointestinal Surgery, Kuopio University Hospital, Puijonlaaksontie 2, FI-70210 Kuopio, Finland. Electronic address: pekka.miettinen@satucon.fi.
authors.forename: Pekka
authors.initials: P
authors.lastname: Miettinen
authors.affiliation: Department of Gastrointestinal Surgery, Kuopio University Hospital, Puijonlaaksontie 2, FI-70210 Kuopio, Finland. Electronic address: petri.juvonen@kuh.fi.
authors.forename: Petri
authors.initials: P
authors.lastname: Juvonen
authors.affiliation: Department of Gastrointestinal Surgery, Kuopio University Hospital, Puijonlaaksontie 2, FI-70210 Kuopio, Finland; University of Eastern Finland, Department of Clinical Medicine, Unit of Surgery, Yliopistonranta 1, FI-70211 Kuopio, Finland. Electronic address: hannu.paajanen@kuh.fi.
authors.forename: Hannu
authors.initials: H
authors.lastname: Paajanen
authors.affiliation: Department of Clinical Radiology, Kuopio University Hospital, Puijonlaaksontie 2, FI-70210, Kuopio, Finland; University of Eastern Finland, Department of Clinical Medicine, Unit of Radiology, Yliopistonranta 1, FI-70211 Kuopio, Finland. Electronic address: ritva.vanninen@kuh.fi.
authors.forename: Ritva
authors.initials: R
authors.lastname: Vanninen
mesh_terms: D000005:Abdomen / Q000000981:diagnostic imaging; D000006:Abdomen, Acute / Q000000981:diagnostic imaging* / Q000191:economics*; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D003362:Cost-Benefit Analysis / Q000191:economics / Q000706:statistics & numerical data; D003952:Diagnostic Imaging / Q000191:economics / Q000379:methods; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data*; D006295:Health Resources / Q000706:statistics & numerical data*; D006801:Humans; D007902:Length of Stay / Q000191:economics / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed / Q000191:economics* / Q000379:methods*; D055815:Young Adult
keywords: Acute abdominal pain; Computed tomography; Cost-effectiveness; Non-specific abdominal pain; Treatment costs