BRiEF
REPORT
Postdischarge, postoperative nosocomial infection surveillance using random sampling Keith A. Frey, MD, MBA Jane Briggs, RN W. Eugene Broadhead, MD, PhD Durham,
North Carolina
Nosocomial infections are an important cause of morbidity and mortality in hospital patients. Nosocomial infections, defined as infections that occur in patients after hospital admission and that were not present or incubating at the time of admission,’ have been estimated to occur in 5% to 6% of hospital patients.’ Nosocomial infection rates are highest on surgical services in all types of hospitals, with the urinary tract the most frequent site, followed by surgical wounds and the lower respiratory tract.L.3 These three sites account for more than 70% of surgical service nosocomial infections.’ Nosocomial infections prolong hospital stays, increase rehospitalization rates, and significantly increase health care costs.’ A retrospective study of 16 literature reports between 1933 and 1975 revealed that hospital stays were prolonged from 1.3 to 26.3 days as a result of nosocomial infections.3 More recent studies have demonstrated that. the average surgical wound infection prolongs the hospital stay by 7.4 days.3 Postoperative nosocomial infections may not be detected until after the patient has been discharged from the hospital. The Centers for Disease Control have suggested at a category III level (to be considered but not recommended for widespread adoption) that discharged patients be contacted 30 days after surgery to determine whether nosocomial infections had ocFrom the Department of Community and Family Medicine, Duke University, and the Infection Control Service, Durham County General Hospital. Reprint Center,
requests: Keith 407 Crutchfield
17/47/20857
A. Frey, MD, MBA, Family St., Durham, NC 27704.
Medicine
curred. The Joint Commission on Accreditation of Healthcare Organizations has made similar recommendations. Several studies5e8 have measured nosocomial infection rates by including the postdischarge recovery period. Each study measured infection rates with use of a census approach, surveying each patient and/or physician for a defined period. Although valuable data were collected, the cost of implementing such complete postdischarge surveillance would be prohibitively expensive (in personnel costs) for most hospitals.’ This study was undertaken with the hypothesis that random samples of surgeon-recalled postdischarge, postoperative infections would establish nosocomial infection rates that were comparable to those in census surveys If this hypothesis could be supported, then more efficient and less costly methods of postdischarge surveillance could be developed. METHODS Durham County General Hospital is a 450bed community hospital with a major teaching affiliation with Duke University Medical Center. Approximately 7200 surgical procedures are performed annually by 90 attending surgeons. A computer-generated list of all surgical cases from the previous month was obtained each month, and the cases were numbered consecutively. The study was limited to the general surgery service, and only category I and II (clean and clean-contaminated) cases were studied. The previous months’ surgical cases were randomized, and a 20% sample was selected. The monthly sampling continued during a 13-month period from August 1988 through
American
384
Frey
et al.
INFECTION
Table 1. Return rate of postoperative nosocomial infection questionnaires sent to surgeons at a community hospital Molyr (No. of oases’)
No. sampled and questionnaires sent
8/88(440)
9/88
105 77
(397)
10/88(402)
111 108
11/88 (406) l/89 (356) 2/89(377) 3/89(388) 4/89(425) 5/89(421) 6/89(403)
TOTAL
% returned
81 55 80
77 71 72
96
89 96 89
84 85
81 76
76 80 73
64
84
79
99 92
67
69
76 70
7/89(434) 8/89(442)
Rebmed
72 1017
64
91 91
65
90
877
86
(average) ‘Represents category I and II surgical cases per month at the community hospital. No cases were surveyed in December 1988 because of holiday surgical schedules.
Journal
of
CONTROL
was obtained and the study was explained to department members by the chairman with written materials provided by the investigators. For each surgical case selected, a brief questionnaire was placed in the attending surgeon’s box in the physician lounge. A box for questionnaire returns was conveniently located in the same lounge. The surgeons responding to the questionnaire were expected to rely on their own recall to address each question. The study was designed to survey for the surgeon’s recall of postoperative, posthospitalization infection by sampling in the month after the patient’s surgery. It was anticipated that most patients would have been seen by the surgeon for at least one postoperative check because of the length of time elapsed from surgery to the time of sampling. No attempt was made to follow up on surveys not completed or returned by the selected surgeon. RESULTS
Table 2. Postdischarge nosocomial infections noted by surgeon recall by infection site from random sampling of 877 surgical cases Infections Molyr’
Wound
u-n
noted Pulmonary
8188
0
9188 10188
2 1
3 1 0
11/88
2 0
2 1
3189 4189 5189
1 1
0 0
0 0
0 0
6189
0
0
0
7189
s! 7
1
9 3
l/89 2189
TOTAL
UT/. Urinary tract infection. “No surgical cases were surveyed surgical schedules.
1 0 1 1 0 0 0 0 0
8
in December
1988 because
of holiday
August 1989. No sampling was performed for the surgical cases done in December 1988 because of the lighter holiday surgical schedule. Before the beginning of the study, the support of the chairman of the department of surgery
Table 1 lists the return rate of the postoperative, postdischarge nosocomial infection questionnaires sent to the surgeons in randomly selected cases. A total of 1017 cases were randomly selected during the 13-month study period, with an average of 85 selected per month (range 70 to 111). A total of 877 were returned from the surgeons, for a return rate of 86.2% during the entire study. Table 2 provides the specific postdischarge nosocomial infections noted by surgeon recall (on the questionnaire), by the infection site. Eighteen postdischarge nosocomial infections were recorded by surgeon recall. Of these 18, seven were noted to be wound infections, eight urinary tract infections, and three pulmonary tract infections. No other sites of infection were recalled and noted by the attending surgeons. DISCUSSION
The nosocomial infection rate in our hospital in the surgical service during the study period, using standard reporting criteria, was 4.52%. The additional 18 postoperative, postdischarge infections recalled by attending surgeons were from approximately 20% of the annual surgical cases in categories I and II. Our estimated rate
Volume December
18 Number
6
1990
of 2.05% (95% confidence limits, 1.11% to 2.99%) corresponds to an estimated 90 additional postdischarge infections when extrapolated to all surgical cases in these categories and to a total surgical nosocomial infection rate of 6.57% for the period studied. This assumes that no other infections would have been identified from the unreturned questionnaires. A previous study’ reviewed all operations during a 3-month period and surveyed both patients and surgeons for nosocomial infections. Nearly half (46.3%) the surgical infections were detected only after discharge. The rate of infection for clean and clean-contaminated cases was 6.5%, when the in-hospital and posthospital components of this patient and surgeon recall study were combined. These findings were similar to the rates established in our study with use of a random sample of surgeon recall only. The use of random sampling to assess posthospital rates of infection provides a practical approach. The methods described in previous studieP require intense staff effort and are therefore expensive and often impractical. This study demonstrates that random sampling of a sufficient proportion of surgical cases can establish infection rates that are similar to census data. Further follow-up study will be required with the use of chart audits and patient recall to evaluate the validity of the methods described in this study. This study was dependent on the surgeon’s recall and is probably an underestimate of the true rate. Furthermore, these results are not likely to be useful to identify problems resulting from a particular surgeon’s technique but may be helpful in identifying any systematic problems that would result in increased rates of nosocomial infections.
Postdischarge nosocomial infection surveillance
385
The described study could provide the community hospital with a methodology to broadly monitor postoperative nosocomial rates more comprehensively and economically. If randomly sampled rates rise above established and acceptable ranges, then targeted surveying could and should be initiated. This study focused on clean and clean-contaminated general surgical cases in a community hospital. The study design should be evaluated in different patient mixes and in different hospital settings. We thank Ms. Lisa McCullock, medical records technician, for her assistance in coding and running the necessary reports for successful completion of this study.
References 1. Scheckler WE. Nosocomial infections in a community hospital, 1972 through 1976. Arch Intern Med 1978; 138:1792-94. 2. Jarvis WR, White JW, Munn VP, et al. Nosocomial infection surveillance-1983. MMWR 1983;33:9SS21SS. 3. Brachman PS, Dan BB, Haley RW, Hooton TM, Garner JS, Allen JR. Nosocomial surgical infections: incidence and cost. Surg Clin North Am 1980;60:15-25. 4. Wenzel RP, Hunting KJ, Ostermann CA. Postoperative wound infection rates. Surg Gynecol Obstet 1977;144: 749-52. 5. Brown RB, Bradley S, Opitz E, Cipriani D, Pieczarka R, Sands M. Surgical wound infections documented after hospital discharge. AM J INFECT CONTROL 1987;15:54-8. 6. Burns SJ, Dippe SE. Postoperative wound infections detected during hospitalization and after discharge in a community hospital. AM J INFECT CONTROL 1982;lO: 60-S. 7. Rosendorf LL, Octavia J, Estes JP. Effect of methods of postdischarge wound infection surveillance on reported infection rates. AM J INFECT CONTROL 1983; 11:226-9. 8. Garvey JM, Buffenmyer C, Rycheck RR, Yee R, McVay J, Harger JH. Surveillance for postoperative infections in outpatient gynecologic surgery. AM J INFECT CONTROL 1986;7:54-8.
REPORT
Postdischarge, postoperative nosocomial infection surveillance using random sampling Keith A. Frey, MD, MBA Jane Briggs, RN W. Eugene Broadhead, MD, PhD Durham,
North Carolina
Nosocomial infections are an important cause of morbidity and mortality in hospital patients. Nosocomial infections, defined as infections that occur in patients after hospital admission and that were not present or incubating at the time of admission,’ have been estimated to occur in 5% to 6% of hospital patients.’ Nosocomial infection rates are highest on surgical services in all types of hospitals, with the urinary tract the most frequent site, followed by surgical wounds and the lower respiratory tract.L.3 These three sites account for more than 70% of surgical service nosocomial infections.’ Nosocomial infections prolong hospital stays, increase rehospitalization rates, and significantly increase health care costs.’ A retrospective study of 16 literature reports between 1933 and 1975 revealed that hospital stays were prolonged from 1.3 to 26.3 days as a result of nosocomial infections.3 More recent studies have demonstrated that. the average surgical wound infection prolongs the hospital stay by 7.4 days.3 Postoperative nosocomial infections may not be detected until after the patient has been discharged from the hospital. The Centers for Disease Control have suggested at a category III level (to be considered but not recommended for widespread adoption) that discharged patients be contacted 30 days after surgery to determine whether nosocomial infections had ocFrom the Department of Community and Family Medicine, Duke University, and the Infection Control Service, Durham County General Hospital. Reprint Center,
requests: Keith 407 Crutchfield
17/47/20857
A. Frey, MD, MBA, Family St., Durham, NC 27704.
Medicine
curred. The Joint Commission on Accreditation of Healthcare Organizations has made similar recommendations. Several studies5e8 have measured nosocomial infection rates by including the postdischarge recovery period. Each study measured infection rates with use of a census approach, surveying each patient and/or physician for a defined period. Although valuable data were collected, the cost of implementing such complete postdischarge surveillance would be prohibitively expensive (in personnel costs) for most hospitals.’ This study was undertaken with the hypothesis that random samples of surgeon-recalled postdischarge, postoperative infections would establish nosocomial infection rates that were comparable to those in census surveys If this hypothesis could be supported, then more efficient and less costly methods of postdischarge surveillance could be developed. METHODS Durham County General Hospital is a 450bed community hospital with a major teaching affiliation with Duke University Medical Center. Approximately 7200 surgical procedures are performed annually by 90 attending surgeons. A computer-generated list of all surgical cases from the previous month was obtained each month, and the cases were numbered consecutively. The study was limited to the general surgery service, and only category I and II (clean and clean-contaminated) cases were studied. The previous months’ surgical cases were randomized, and a 20% sample was selected. The monthly sampling continued during a 13-month period from August 1988 through
American
384
Frey
et al.
INFECTION
Table 1. Return rate of postoperative nosocomial infection questionnaires sent to surgeons at a community hospital Molyr (No. of oases’)
No. sampled and questionnaires sent
8/88(440)
9/88
105 77
(397)
10/88(402)
111 108
11/88 (406) l/89 (356) 2/89(377) 3/89(388) 4/89(425) 5/89(421) 6/89(403)
TOTAL
% returned
81 55 80
77 71 72
96
89 96 89
84 85
81 76
76 80 73
64
84
79
99 92
67
69
76 70
7/89(434) 8/89(442)
Rebmed
72 1017
64
91 91
65
90
877
86
(average) ‘Represents category I and II surgical cases per month at the community hospital. No cases were surveyed in December 1988 because of holiday surgical schedules.
Journal
of
CONTROL
was obtained and the study was explained to department members by the chairman with written materials provided by the investigators. For each surgical case selected, a brief questionnaire was placed in the attending surgeon’s box in the physician lounge. A box for questionnaire returns was conveniently located in the same lounge. The surgeons responding to the questionnaire were expected to rely on their own recall to address each question. The study was designed to survey for the surgeon’s recall of postoperative, posthospitalization infection by sampling in the month after the patient’s surgery. It was anticipated that most patients would have been seen by the surgeon for at least one postoperative check because of the length of time elapsed from surgery to the time of sampling. No attempt was made to follow up on surveys not completed or returned by the selected surgeon. RESULTS
Table 2. Postdischarge nosocomial infections noted by surgeon recall by infection site from random sampling of 877 surgical cases Infections Molyr’
Wound
u-n
noted Pulmonary
8188
0
9188 10188
2 1
3 1 0
11/88
2 0
2 1
3189 4189 5189
1 1
0 0
0 0
0 0
6189
0
0
0
7189
s! 7
1
9 3
l/89 2189
TOTAL
UT/. Urinary tract infection. “No surgical cases were surveyed surgical schedules.
1 0 1 1 0 0 0 0 0
8
in December
1988 because
of holiday
August 1989. No sampling was performed for the surgical cases done in December 1988 because of the lighter holiday surgical schedule. Before the beginning of the study, the support of the chairman of the department of surgery
Table 1 lists the return rate of the postoperative, postdischarge nosocomial infection questionnaires sent to the surgeons in randomly selected cases. A total of 1017 cases were randomly selected during the 13-month study period, with an average of 85 selected per month (range 70 to 111). A total of 877 were returned from the surgeons, for a return rate of 86.2% during the entire study. Table 2 provides the specific postdischarge nosocomial infections noted by surgeon recall (on the questionnaire), by the infection site. Eighteen postdischarge nosocomial infections were recorded by surgeon recall. Of these 18, seven were noted to be wound infections, eight urinary tract infections, and three pulmonary tract infections. No other sites of infection were recalled and noted by the attending surgeons. DISCUSSION
The nosocomial infection rate in our hospital in the surgical service during the study period, using standard reporting criteria, was 4.52%. The additional 18 postoperative, postdischarge infections recalled by attending surgeons were from approximately 20% of the annual surgical cases in categories I and II. Our estimated rate
Volume December
18 Number
6
1990
of 2.05% (95% confidence limits, 1.11% to 2.99%) corresponds to an estimated 90 additional postdischarge infections when extrapolated to all surgical cases in these categories and to a total surgical nosocomial infection rate of 6.57% for the period studied. This assumes that no other infections would have been identified from the unreturned questionnaires. A previous study’ reviewed all operations during a 3-month period and surveyed both patients and surgeons for nosocomial infections. Nearly half (46.3%) the surgical infections were detected only after discharge. The rate of infection for clean and clean-contaminated cases was 6.5%, when the in-hospital and posthospital components of this patient and surgeon recall study were combined. These findings were similar to the rates established in our study with use of a random sample of surgeon recall only. The use of random sampling to assess posthospital rates of infection provides a practical approach. The methods described in previous studieP require intense staff effort and are therefore expensive and often impractical. This study demonstrates that random sampling of a sufficient proportion of surgical cases can establish infection rates that are similar to census data. Further follow-up study will be required with the use of chart audits and patient recall to evaluate the validity of the methods described in this study. This study was dependent on the surgeon’s recall and is probably an underestimate of the true rate. Furthermore, these results are not likely to be useful to identify problems resulting from a particular surgeon’s technique but may be helpful in identifying any systematic problems that would result in increased rates of nosocomial infections.
Postdischarge nosocomial infection surveillance
385
The described study could provide the community hospital with a methodology to broadly monitor postoperative nosocomial rates more comprehensively and economically. If randomly sampled rates rise above established and acceptable ranges, then targeted surveying could and should be initiated. This study focused on clean and clean-contaminated general surgical cases in a community hospital. The study design should be evaluated in different patient mixes and in different hospital settings. We thank Ms. Lisa McCullock, medical records technician, for her assistance in coding and running the necessary reports for successful completion of this study.
References 1. Scheckler WE. Nosocomial infections in a community hospital, 1972 through 1976. Arch Intern Med 1978; 138:1792-94. 2. Jarvis WR, White JW, Munn VP, et al. Nosocomial infection surveillance-1983. MMWR 1983;33:9SS21SS. 3. Brachman PS, Dan BB, Haley RW, Hooton TM, Garner JS, Allen JR. Nosocomial surgical infections: incidence and cost. Surg Clin North Am 1980;60:15-25. 4. Wenzel RP, Hunting KJ, Ostermann CA. Postoperative wound infection rates. Surg Gynecol Obstet 1977;144: 749-52. 5. Brown RB, Bradley S, Opitz E, Cipriani D, Pieczarka R, Sands M. Surgical wound infections documented after hospital discharge. AM J INFECT CONTROL 1987;15:54-8. 6. Burns SJ, Dippe SE. Postoperative wound infections detected during hospitalization and after discharge in a community hospital. AM J INFECT CONTROL 1982;lO: 60-S. 7. Rosendorf LL, Octavia J, Estes JP. Effect of methods of postdischarge wound infection surveillance on reported infection rates. AM J INFECT CONTROL 1983; 11:226-9. 8. Garvey JM, Buffenmyer C, Rycheck RR, Yee R, McVay J, Harger JH. Surveillance for postoperative infections in outpatient gynecologic surgery. AM J INFECT CONTROL 1986;7:54-8.
