Proactive Risk Assessment of Surgical Site Infection in Ambulatory Surgery Centers

Appendix G. References for Fault Tree Model Probability Estimates

Identifier Description Input Value Reference
Event115 Poor hygiene while dressing 0.1 Best guess
Event116 Linen contaminated 0.05 Best guess
Event136 Fail to wash hands properly (OR staff) 0.12 Sharir et al. 2001—literature indicates this probability is in general much lower (around 12%) for OR staff doing invasive procedures than other staff (where it can be as high as 40%)
Event138 Fail to remove watch/jewelry/fake nails 0.15 Kennedy et al. 2004—this is a conservative estimate, can be as high as 30-40%
Event142 Staff not well-trained in infection control 0.3 Babcock et al. 2002 based on multi-institutional survey, but highly depends on the site; sensitivity analysis needed
Event145 Skin lesion near incision site 0.001 Prevalence of skin lesion estimated at 0.002, split equally  btw Ev 145 and 147
Event146 Fail to halt opern prior to identifying skin lesion 0.001 Best guess (sub-TEP indicated the probability of this failure was small)
Event147 Open skin lesions (entire body) 0.001 Prevalence of skin lesion estimated at 0.002, split equally  btw Ev 145m 147
Event148 Fail to schedule OP after infections are resolved 0.001 Best guess (sub-TEP indicated the probability of this failure was small)
Event169 Other pt SSI risk 0.00046 Calculated from other probability estimates in the model (1—proportion of all other patient types connected to Gate 2)
Event173 Staff fails to provide pt with instruction (for weight reduction) 0.9 From Tony (not done in ASCs at  all, so 0.9 is a conservative estimate, implying this is done 10% of the time)
Event182 Fail to administer indicated antibiotics 0.2 Burke et al. 2001, Silver et al. 1996., Van Kasteren et al. 2007 (high variation in estimates, ranging from 20% to 60% — sensitivity analysis req'd)
Event192 Fail to use correct antiseptic 0.003 Gt 236=0.125 (fail to prep appropriately, from Babcock et al. 2003), split equally among Ev 192, 193, 613, 614. So = 0.125/4=0.003125
Event193 Fail to use for appropriate time 0.003 Gt 236=0.125 (fail to prep appropriately, from Babcock et al. 2003), split equally among Ev 192, 193, 613, 614. So = 0.125/4=0.003125
Event203 Fail to wash hand (non-OR staff) 0.38 Sharir et al. 2001
Event21 Pt fails to follow instruction (for smoking cessation) 0.13 From Tony, proportion of pts who do not disclose smoking status is 50% (agrees with the literature; Schofield et al indicates this is 40%). For smokers who disclose their status (50% of them), 13-15% will not follow instructions for smoking cessation.
Event210 Lack of 2 filter beds in series 0.00625 Gt 105 improper ventilation system=0.05 (best guess), equally split among Ev 210, 612, 213, 611, 325, 328, 326, 327
Event213 Not introducing air at ceiling 0.00625 Gt 105 improper ventilation system=0.05 (best guess), equally split among Ev 210, 612, 213, 611, 325, 328, 326, 327
Event220 For visible soiling, fail to use disinfection aft OP 0.000033 From Tony, Fail to clean OR=0.0001 (very small probability), divided equally among Ev 220, 221, and 222.
Event221 Poor routine cleaning after each OP 0.000033 From Tony, Fail to clean OR=0.0001 (very small probability), divide equally among Ev 220, 221, and 222.
Event222 Fail to wet-vacuum floor w/ disinftn after last OP 0.000033 From Tony, Fail to clean OR=0.0001 (very small probability), divide equally among Ev 220, 221, and 222.
Event235 Drape gets contamtd during opern 0.001667 From Tony, Draping-related failure=0.01, split equally among its children events. So 0.01/6=0.001667
Event236 Fail to notice drape not sterilize 0.001667 From Tony, Draping-related failure=0.01, split equally among its children events. So 0.01/6=0.001667
Event237 Drape pulls bug to SS 0.001667 From Tony, Draping-related failure=0.01, split equally among its children events. So 0.01/6=0.001667
Event239 Fail to prevent hypothermia 0.01 From Tony
Event240 Inappropriate use of drain material 0.01 From Tony
Event241 Tourniquet time >60min 0.082 Demers et al. 1998
Event242 Excessive surg time 0.05 Best guess
Event270 Anesthetic risk 0.05 DeLee. 1985
Event28 Pt colonized with MRSA 0.1 Kim et al. 2010, Barbos et al. 2010., large variation, from 4.4% to 37.2%, sensitivity analysis req'd.
Event29 Non-MRSA pt (complement to Gt 28) 0.9 Complement to Ev 28, 1-0.1=0.9
Event30 Fail to prep skin appropriately 0.125 Babcock et al. 2003, Gottrup et al. 2005, variation from 12.5% to 25%
Event306 Not assessed during pre-op visit (obesity) 0.01 Best guess
Event307 Not assessed during pre-op call (obesity) 0.05 From Tony
Event322 Fail to notice drape has holes 0.001667 From Tony, Draping-related failure=0.01, split equally among its children events. So 0.01/6=0.001667
Event323 Break in steril technique/field 0.02 From Tony
Event325 Temp ctrl problems 0.00625 Gt 105 improper ventilation system=0.05 (best guess), equally split btw Ev 210, 612, 213, 611, 325, 328, 326, 327
Event326 Humidity problems 0.00625 Gt 105 improper ventilation system=0.05 (best guess), equally split btw Ev 210, 612, 213, 611, 325, 328, 326, 327
Event327 Air flow problems 0.00625 Gt 105 improper ventilation system=0.05 (best guess), equally split btw Ev 210, 612, 213, 611, 325, 328, 326, 327
Event328 Other (ventilation not working prblems) 0.00625 Gt 105 improper ventilation system=0.05 (best guess), equally split btw Ev 210, 612, 213, 611, 325, 328, 326, 327
Event329 Surgeon fails to inform staff of special needs 0.014286 Gt 64 High traffic in OR=0.1 (Pryor et al., 1998.), equally split btw Ev 329, 610, 330, 331, 332, 333, 334
Event330 Other (fail to min entry/exit and inappr traff pattns) 0.014286 Gt 64 High traffic in OR=0.1 (Pryor et al., 1998.), equally split btw Ev 329, 610, 330, 331, 332, 333, 334
Event331 Lunch breaks 0.014286 Gt 64 High traffic in OR=0.1 (Pryor et al., 1998.), equally split btw Ev 329, 610, 330, 331, 332, 333, 334
Event332 Other (fail to minimize staff changes) 0.014286 Gt 64 High traffic in OR=0.1 (Pryor et al., 1998.), equally split btw Ev 329, 610, 330, 331, 332, 333, 334
Event333 Fail to restrict residents 0.014286 Gt 64 High traffic in OR=0.1 (Pryor et al., 1998.), equally split btw Ev 329, 610, 330, 331, 332, 333, 334
Event334 Fail to restrict family members 0.014286 Gt 64 High traffic in OR=0.1 (Pryor et al., 1998.), equally split btw Ev 329, 610, 330, 331, 332, 333, 334
Event336 Not enough instruments or instrument failure 0.003 DeLee. 1985.
Event34 Fail to shave SS right before procedure 0.01 From Tony; similar % in Mangram et al., 1999.
Event353 Bug moves to pt (fail to decontaminate bug from staff) 0.15 Best guess
Event373 Bug moves to pt (MRSA or other bugs on the stethoscopes) 0.05 Best guess
Event38 Not noticed or managed 0.001 Best guess
Event393 Fail to closure appropriately 0.001 From Tony
Event394 Bug gets to SS (fail to closure appropriately) 0.15 Best guess
Event395 Bug gets to SS (fail to suture appropriately) 0.15 Best guess
Event396 Staff contaminated 0.05 Kim et al. 2010.
Event404 Poor post-op directions to pt 0.15 From Jackson et al. 1991., for 68% of these patients, the mean reading comprehension level was below the ninth grade while most of the commonly used brochures provided to the patients were written at a level far above their ability to comprehend (77% of the materials were written at the eleventh-grade level). Kincey et al. 1975 estimates this as 0.15.
Event405 Pt understands but not follows directions 0.1 Mangram et al. 1999 and Czarneki et al. 2007.
Event417 Pt not available for post-op call 0.15 From Tony
Event418 Nurse fails to recognize infection 0.12 Nurse not assesses 0.16*(1-Event 417)=0.12
Event419 Pt fails to come for post-op visit 0.15 From Tony
Event421 Post-op visit but physicn fails to manage infect 0.01 Mangram et al. 1999
Event422 Fails to notice or mang (pt gets bug during post-op visit) 0.2 Best guess
Event423 Pt gets bug during post-op visit 0.1 Best guess
Event424 Bug moves to SS (pt gets bug dur post-op vst and not mang) 0.01 Best guess
Event433 Pt has bug post-op (pt has bug after post-op visit) 0.05 Best guess
Event45 Inadequate draping 0.001667 From Tony, Draping-related failure=0.01, split equally among its children events. So 0.01/6=0.001667.
Event450 Obese but not diabetes pt (30≤BMI<40) 0.293 33.8% obese (not morbidly obese) in the US adult population. Then Prevalence of obese pt -Ev653 (obese and diabetic)=0.338-0.045=0.293.
Event456 Pt is a smoker and has COPD 0.053395 (proportion of smokers-proportion of elderly smokers)*prevalence of COPD in the smoking population. Adult Cigarette Smoking in US: 20.6% (from CDC). 13.62% patients are elderly (≥65 years of age) in the arthroscopic knee surgery population [CA 2008 SASD]. From Stang et al. 2000., 30% of smokers have COPD. So (0.206-0.1362*0.206)*0.30=0.05338284.
Event459 SSI if bug gets to SS (elderly, not diabetic, and non-smoker) 0.014  Kaye et al. 2005
Event46 Fail to airdry disinf bfr drape 0.001667 From Tony, Draping-related failure=0.01, split equally among its children events. So 0.01/6=0.001667
Event47 Fail to suture appropriately 0.001 From Tony
Event473 Pt w/ vascular compromise in limb 0.01 From Shammas 2007., the prevalence of peripheral vascular disease in the general population is around 10%, so estimated the prevalence of pt w/ vascular compromise in limb as 1%
Event475 SSI if bug gets to SS (pt w/ skin lesion, near incision site and fail to mitigate) 0.03 Best guess
Event476 SSI if bug gets to SS (pt w/ skin lesion, entire body and fail to mitigate) 0.03 Best guess
Event48 Antiseptic not used 0.1 Mangram et al. 1999
Event482 Staff fails to provide pt with instruction (for compromised immune system patients) 0.05 Best guess
Event483 Pt fails to follow instruction (for compromised immune system patients) 0.05 Best guess
Event49 Site not cleansed appropriately 0.1 Best guess
Event494 AIDS pt 0.004 Marks et al. 2006, prevalence of AIDS patients in the US
Event496 Pt with systemic steroid use 0.01 Babcock et al. 2003
Event497 Pt w/ rheumatoid disease 0.05 Grennan et al. 2001
Event498 Cured or not under treatment 0.000031 CA 2008 SASD Database, proportion of cancer patients undergoing arthroscopic surgery used as an estimate of this probability
Event499 SSI if bug gets to SS (cancer pt cured or not under treatment) 0.01 Berbari et al. 1998
Event50 Dressing torn off 0.01 From Tony
Event500 SSI if bug gets to SS (AIDS pt, risk not mitigated) 0.09 Abalo et al. 2010
Event501 Risk mitigated (complement to Gt 249) 0.8 gate 24
Event502 SSI if bug gets to SS (AIDS pt, risk mitigated) 0.06 Abalo et al. 2010
Event503 SSI if bug gets to SS (pt w/ rheumatoid disease) 0.0187 Best guess
Event504 Risk mitigated (complement to Gt 249) 0.8 Complement to Gt 249, so 1-0.2=0.8
Event505 SSI if bug gets to SS(pt w/ rheumatoid disease SSI risk, mitigated) 0.01 Best guess
Event506 SSI if bug gets to SS (pt w/ Systemic steroid use, risk not mitigated) 0.0187 Post et al. 1993
Event507 Risk mitigated (complement to Gt 249) 0.8 Complement to Gt 249, so 1-0.2=0.8
Event508 SSI if bug gets to SS (pt w/ Systemic steroid use, risk mitigated) 0.0187 Assume if mitigated, then risk same as healthy patient
Event509 Pt on Immunosuppressive drugs 0.001 Prevalence in the US is 300,000/300M=0.1%
Event51 Dressing not applied correctly 0.01 From Tony
Event510 SSI if bug gets to SS (pt on Immunosuppressive drugs) 0.0187 Best guess
Event512 Risk mitigated (complement to Gt 249) 0.8 Complement to Gt 249, so 1-0.2=0.8
Event513 SSI if bug gets to SS (Pt on Immunosuppressive drugs, mitigated) 0.01 Best guess
Event516 Fail to assess during vitals check 0.0005 Best guess (very small)
Event517 Fail to reschedule OP (after high temp assessed) 0.0005 Best guess (very small)
Event519 Glucose level controlled pre-op (Gt 10 complement) 0.97 Gt 10 complement
Event52 IV phlebitis 0.016 Arjona et al. 1997
Event520 Glucose level not controlled post-op 0.27 Latham et al. 2001
Event521 SSI if bug gets to SS (diabetes (not obese) pt, GL controlled pre-op but not post-op) 0.03 Boulton et al. 2005.
Event522 SSI if bug gets to SS (diabetes (not obese) pt, GL controlled post-op but not pre-op) 0.03 Boulton et al. 2005.
Event523 Glucose level controlled post-op 0.73 Latham et al. 2001
Event524 Glucose level controlled pre-op 0.97 same as Event 519
Event525 SSI if bug gets to pt (diabetes  (not obese) pt,GL controlled, pre-op and post-op) 0.02 Boulton et al. 2005.
Event526 Glucose level controlled post-op 0.73 same as Event 523
Event527 Glucose level not controlled post-op 0.27 same as Event 520
Event528 SSI if bug gets to pt (diabetes (not obese) pt, GL fail to control pre-op and post op) 0.077 Latham et al. 2001
Event529 Malnourished pt 0.001 From Tony (very small proportion of malnourished pts in the US)
Event53 Pt hands contaminated 0.05 Best guess
Event530 Nutritional status not improved pre-op 1 From Tony (ASCs do not assess nutritional status)
Event531 SSI if bug gets to SS (malnourished pt, not mitigated) 0.05 Klein et al. 1996
Event539 Alcoholic 0.04 Spies et al. 2004 (proportion of alcoholism in the US population)
Event543 SSI if bug gets to SS (obese pt, weight not redcd and nutrition not impr) 0.0325 Olsen et al. 2008
Event544 Weight  reduced and nutrition impr 0.1 Best guess (not routinely done in ASCs for obese pts)
Event545 SSI if bug gets to SS (obese pt, weight reduced and nutrition impr) 0.01 Best guess
Event546 Pt does not provide accurate info 0.37 From Schofield et al. 1999, smoking self-disclosure rate=0.63, so 1-0.63=0.37
Event550 Acute risk 0.03 from Myles et al. 2002, smoker SSI risk split equally btw Ev 550, 558
Event552 Stp smk pre-op but starts in rec phase 0.2 Complement of Gt 14, 0.5*0.4=0.2. From Evangelista et al. 2000., compliance rates range from 10%-85% depending on the population and the medical regimen studied. Estimated that pt lack of compliance w/ discharge orders=40%
Event553 Acute risk 0.03 Myles et al. 2002, smoker SSI risk split equally btw Ev 553, 554
Event554 Chronic risk (underlying heart disease) 0.03 Myles et al. 2002, smoker SSI risk split equally btw Ev 553, 554
Event555 Pt stops smoking pre-op and post-op 0.3 (1-Gt 14)*pt complies post-op=(1-0.5)*0.6=0.3
Event558 Chronic risk (underlying heart disease) 0.03 Myles et al. 2002, smoker SSI risk split equally btw Ev 550, 558
Event561 SSI if bug gets to SS (pt w/ vascular compromise in limb) 0.02 Best guess
Event591 Bug moves to SS (due to inappropriate prep) 0.692 From Kim et al. 2010, for MRSA patients
Event592 Bug moves to SS (due to inappropriate prep) 0.1 Best guess
Event593 Staff w/ active skin infection 0.0525 From Jeans et al. 2010., rate of S. aureus carriage in health-care workers: 10.5%-39.7%, conservative estimate of 10.5% split btw Ev 593, 594
Event594 Other (rather than staff w/ active skin infection) 0.0525 From Jeans et al. 2010., rate of S. aureus carriage in health-care workers: 10.5%-39.7%, conservative estimate of 10.5% split btw Ev 593, 594
Event599 Fail to report infection 0.01 Mangram et al. 1999
Event605 Infection subtle 0.04 Best guess
Event610 Inappropriate traffic patterns 0.014286 Gt 64 High traffic in OR=0.1 (Pryor et al., 1998.), equally split btw Ev 329, 610, 330, 331, 332, 333, 334
Event611 Improper air exchange 0.00625 Gt 105 improper ventilation system=0.05 (best guess), equally split btw Ev 210, 612, 213, 611, 325, 328, 326, 327
Event612 Insufficient efficiency 0.00625 Gt 105 improper ventilation system=0.05 (Pryor et al., 1998.), equally split btw Ev 210, 612, 213, 611, 325, 328, 326, 327
Event613 Contaminating the site 0.003 Gt 236=0.125 (fail to prep appropriately, from Babcock et al. 2003), split equally among Ev 192, 193, 613, 614. So=0.125/4=0.003125
Event614 Cleansing from dirty to clean 0.003 Gt 236=0.125 (fail to prep appropriately, from Babcock et al. 2003), split equally among Ev 192, 193, 613, 614. So=0.125/4=0.003125
Event618 SSI if bug gets to SS (alcoholic pt, mitigated) 0.01 Best guess
Event619 SSI if bug gets to SS (alcoholic pt, not mitigated) 0.026 Spies et al.2004.
Event621 Pt does not provide accurate info (on alcoholic status) 0.37 Schofield et al. 1999., 63% of patients revealed to admission staff that they were alcoholic, so 1-0.63=0.37
Event622 Pt fails to comply with instruction (on stopping drinking—alcoholic pt) 0.13 Event 21 estimate (for smokers) used here also
Event624 Mitigated (for alcoholic pt) 0.5 From Tony
Event625 Glucose level not controlled pre-op 0.03 From Tony
Event627 Fail to assess, ctrl pre-op and postpone surg (vascular compromise in limb) 1 From Tony
Event628 GLl not controlled pre-op (Ev 519 complement) 0.03 Event 519 complement, 1-0.97=0.03
Event630 Acute and chronic risk (pt stops smoking pre-op and post-op) 0.01 Best guess
Event631 Fail to assess compromised immu sys 0.1 Best guess
Event632 Dialysis pt 0.001 As of 2007 there were 368,544 US residents with end stage renal disease receiving dialysis. (Kidney diseases), estimated as 0.001
Event633 Fail to screen pre-op (for MRSA) (dialysis pt) 1 Routine MRSA test not done—site visits
Event634 Fail to screen pre-op (for MRSA) (elderly pt) 1 Routine MRSA test not done -site visits
Event635 Elderly pt 0.1362 From CA 2008 SASD
Event636 Fail to screen pre-op (for MRSA) (nursing home pt) 1 Routine MRSA test not done-site visits
Event637 Nursing home pt 0.005 Jones et al. 2009., as of 2004 there were 1,492,200 nursing home patients in the USA, estimated as 0.005
Event638 Fail to screen pre-op (for MRSA) (pt with history of MRSA) 1 Routine MRSA test not done-site visits
Event639 Pt with history of MRSA 0.002 Klein et al. 2007. The estimated number of MRSA hospitalizations in 2005 was 278,203, estimated as 0.002
Event640 Fail to screen pre-op (for MRSA) (other pt) 1 Routine MRSA test not done-site visits
Event641 Other pt 0.8558 1-all the non "other pts", such as dialysis pt, etc.
Event642 Bug gets to pt (fail to protect pt effectively) 0.2 Best guess
Event643 Bug gets to pt (surgical procedure puts pt at higher risk) 0.2 Best guess
Event644 Fail to readmin (antibiotics) for longer surgery 0.1 Burke et al. 2001., Silver et al. 1996., Van Kasteren et al. 2007.
Event645 Morbidly obese pt (BMI>=40) 0.057 CDC web site and Flegal et al. 2002.
Event647 Elderly, diabetic, and non-smoker 0.020644 Elderly pt prevalence*percentage of elderly diabetic pt*(1-prevalence of smokers). Elderly pt prevalence= 13.62%  [CA 2008 SASD arthroscopic knee surgery patient population]. Percentage of elderly diabetic pt = 19% [http://www.cdc.gov/diabetes/statistics/prev/national/figbyage.htm]. Prevalence of smokers in the US =20.6% (CDC). So 0.1362*0.19*(1-0.206)=0.0206
Event648 Elderly, not diabetic, and non-smoker 0.08734 Elderly pt prevalence*(1-percentage of elderly diabetic pt)*(1-prevalence of smokers). Elderly pt prevalence= 13.62% [CA 2008 SASD arthroscopic knee surgery patient population]. Percentage of elderly diabetic pt = 19% [http://www.cdc.gov/diabetes/statistics/prev/national/figbyage.htm].  Prevalence of smokers in the US =20.6% (CDC). So 0.1362*(1-0.19)*(1-0.206)=0.087
Event649 SSI if bug gets to SS (elderly, diabetic, and non-smoker) 0.0378 Olsen et al. 2002.
Event651 Diabetes pt not diagnosed 0.026 It is estimated that 23.6 million people are afflicted in the United States, accounting for  approximately 7.8% of the population. Nearly one third of persons with diabetes are unaware that they have DM. Boulton et al. 2005.
Event652 SSI if bug gets to SS (diabetes pt not diagnosed) 0.02 Boulton et al. 2005.
Event653 Diabetes and obese pt 0.045 38.6% of the obese suffer diabetes [http://usgovinfo.about.com/library/weekly/aa010803a.htm]. Prevalence of obese pt who are diabetics around 4.5%
Event654 Diabetes but not obese pt 0.007 From McMillen 2011, nearly one third of persons with diabetes are unaware that they have DM. So two thirds of the diabetes pt-diabetes and obese pt=0.078*(2/3)-0.045=0.007
Event655 SSI if bug gets to SS (diabetes (and obese) pt, GL controlled pre-op but not post-op) 0.077 Olsen et al. 2002.
Event656 SSI if bug gets to SS (diabetes (and obese) pt, GL controlled post-op but not pre-op) 0.077 Olsen et al. 2002.
Event657 SSI if bug gets to pt (diabetes  (and obese) pt,GL controlled, pre-op and post-op) 0.04 Olsen et al. 2008
Event658 SSI if bug gets to pt (diabetes (and obese) pt, GL fail to control pre-op and post op) 0.1 Boulton et al. 2005.
Event659 Glove puncture 0.18 Duke Infection Control Group 2011.
Event660 Pt fails to notice infection 0.16 Mangram et al. 1999
Event670 Elderly, diabetic,  and smoker 0.005356 Elderly pt prevalence *percentage of elderly diabetic pt* prevalence of smokers. Elderly pt prevalence= 13.62% [CA 2008 SASD arthroscopic knee surgery patient population]. Percentage of elderly diabetic pt = 19% [http://www.cdc.gov/diabetes/statistics/prev/national/figbyage.htm]. Prevalence of smokers in the US=20.6% (CDC). So 0.1362*0.19*0.206=0.0053
Event671 SSI if bug gets to SS (elderly, diabetic, and smoker) 0.1134 Olsen et al. 2002.
Event672 Elderly, not diabetic, and smoker 0.02266 Elderly pt prevalence*(1-percentage of elderly diabetic pt)*prevalence of smokers. Elderly pt prevalence= 13.62% [CA 2008 SASD arthroscopic knee surgery patient population]. Percentage of elderly diabetic pt = 19% [http://www.cdc.gov/diabetes/statistics/prev/national/figbyage.htm]. Prevalence of smokers in the US =20.6% (CDC). So 0.1362*(1-0.19)*0.206=0.02
Event673 SSI if bug gets to SS (smoker and elderly, not diabetic) 0.042 Kaye et al. 2005.
Event674 MRSA or other bugs on the stethoscopes 0.32 Merlin et al. 2009
Event676 SSI if bug gets to SS (malnourished pt, mitigated) 0.01 Assume, when mitigated, risk same as healthy pt
Event677 Pt is a smoker but has no COPD 0.124589 (prevalence of smokers-elderly smokers)*(1-prevalence of COPD in the smoking population). Adult Cigarette Smoking in US: 20.6% (CDC). % elderly patients (>=65 years of age) in the arthroscopic knee surgery population is 13.62% [CA 2008 SASD arthroscopic knee surgery patient population]. From Stang et al. 2000., 30% of smokers have COPD. So (0.206-0.1362*0.206)*(1-0.30)=0.12458
Event678 Stp smk pre-op but starts in rec phase 0.2 Same as Ev552
Event679 Pt stops smoking pre-op and post-op 0.3 Same as Ev555
Event680 Acute and chronic risk (pt stops smoking pre-op and post-op) 0.01 Assume, when mitigated, risk same as health pt
Event682 Pt fails to follow instruction 0.13 Same as Ev21
Event683 Acute risk (COPD) 0.06 Best guess
Event684 Chronic risk (underlying heart disease, COPD) 0.06 Best guess
Event685 Acute risk (COPD) 0.06 Best guess
Event686 Chronic risk (underlying heart disease, COPD) 0.06 Best guess
Event687 Pt does not provide accurate info 0.37 Same as Event 621
Page last reviewed April 2013
Internet Citation: Appendix G. References for Fault Tree Model Probability Estimates. April 2013. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/research/findings/final-reports/stpra/stpraapg.html