Global quantitative indices reflecting provider process-of-care: data-base derivation.
BACKGROUND
Controversy has attended the relationship between risk-adjusted mortality and process-of-care. There would be advantage in the establishment, at the data-base level, of global quantitative indices subsuming the diversity of process-of-care.


METHODS
A retrospective, cohort study of patients identified in the Australian and New Zealand Intensive Care Society Adult Patient Database, 1993-2003, at the level of geographic and ICU-level descriptors (n = 35), for both hospital survivors and non-survivors. Process-of-care indices were established by analysis of: (i) the smoothed time-hazard curve of individual patient discharge and determined by pharmaco-kinetic methods as area under the hazard-curve (AUC), reflecting the integrated experience of the discharge process, and time-to-peak-hazard (TMAX, in days), reflecting the time to maximum rate of hospital discharge; and (ii) individual patient ability to optimize output (as length-of-stay) for recorded data-base physiological inputs; estimated as a technical production-efficiency (TE, scaled [0,(maximum)1]), via the econometric technique of stochastic frontier analysis. For each descriptor, multivariate correlation-relationships between indices and summed mortality probability were determined.


RESULTS
The data-set consisted of 223129 patients from 99 ICUs with mean (SD) age and APACHE III score of 59.2(18.9) years and 52.7(30.6) respectively; 41.7% were female and 45.7% were mechanically ventilated within the first 24 hours post-admission. For survivors, AUC was maximal in rural and for-profit ICUs, whereas TMAX (>or= 7.8 days) and TE (>or= 0.74) were maximal in tertiary-ICUs. For non-survivors, AUC was maximal in tertiary-ICUs, but TMAX (>or= 4.2 days) and TE (>or= 0.69) were maximal in for-profit ICUs. Across descriptors, significant differences in indices were demonstrated (analysis-of-variance, P <or= 0.0001). Total explained variance, for survivors (0.89) and non-survivors (0.89), was maximized by combinations of indices demonstrating a low correlation with mortality probability.


CONCLUSIONS
Global indices reflecting process of care may be formally established at the level of national patient data-bases. These indices appear orthogonal to mortality outcome.
Moran
John L
JL
Department of Intensive Care Medicine, The Queen Elizabeth Hospital, Woodville SA 5011, Australia. john.moran@adelaide.edu.au
Solomon
Patricia J
PJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001315:Australia; D015331:Cohort Studies; D016208:Databases, Factual; D005069:Evaluation Studies as Topic; D005260:Female; D017052:Hospital Mortality; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007362:Intensive Care Units / Q000191:economics / Q000592:standards* / Q000706:statistics & numerical data; D007902:Length of Stay / Q000706:statistics & numerical data; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D017059:Models, Econometric; D009520:New Zealand; D011336:Probability; D017064:Process Assessment, Health Care / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D017741:Survivors / Q000706:statistics & numerical data
Med Care Res Rev. 1998 Dec;55(4):371-404
9844348
Health Care Manag Sci. 2003 Feb;6(1):43-55
12638926
JAMA. 2002 Nov 6;288(17):2151-62
12413375
Chest. 1991 Dec;100(6):1619-36
1959406
Hosp Health Serv Adm. 1997 Winter;42(4):489-507
10174462
Int J Qual Health Care. 2001 Dec;13(6):475-80
11769750
N Engl J Med. 1987 Dec 24;317(26):1674-80
3683509
Stat Med. 1990 May;9(5):469-85
2349401
N Engl J Med. 2002 May 30;346(22):1715-22
12037152
Med Care. 2003 May;41(5):575-8
12719679
Med Care. 2007 Jun;45(6):489-96
17515775
Int J Health Care Qual Assur Inc Leadersh Health Serv. 1997;10(2-3):117-24
10169231
J Crit Care. 2006 Jun;21(2):133-41
16769456
Int J Qual Health Care. 2001 Dec;13(6):489-96
11769752
Med J Aust. 2007 Nov 19;187(10):571-5
18021046
Crit Care Resusc. 2003 Dec;5(4):292-304
16563120
Crit Care. 2006 Feb;10(1):103
16420653
Ann Intern Med. 1986 Mar;104(3):410-8
3946981
Pediatrics. 2004 Oct;114(4):e400-8
15466064
Med Care. 2003 Mar;41(3):386-97
12618642
Med Care Res Rev. 2004 Jun;61(2):135-70
15155049
BMC Health Serv Res. 2007 Jun 20;7:91
17584919
Health Serv Res. 1999 Apr;34(1 Pt 2):349-63
10199680
N Engl J Med. 2005 Jul 21;353(3):255-64
16034011
JAMA. 2006 Dec 13;296(22):2694-702
17164455
JAMA. 1991 Jul 3;266(1):73-9
2046132
Stat Med. 2000 May 15;19(9):1141-64
10797513
Crit Care Med. 1994 Sep;22(9):1385-91
8062559
Med Care Res Rev. 2008 Apr;65(2):131-66
18045984
Intensive Care Med. 1996 Jul;22(7):664-9
8844231
Health Serv Res. 2003 Jun;38(3):867-86
12822916
J Eval Clin Pract. 1997 Aug;3(3):187-99
9406106
JAMA. 2008 May 21;299(19):2322-3
18492975
Crit Care Med. 2008 Jan;36(1):46-61
18090383
JAMA. 2006 Dec 13;296(22):2731-2
17164460