The Second National Prevalence Survey of Infection in Hospitals—overview of the results

Journal

Infection

of Hospital

(1996)

32, 175-190

The Second National Prevalence Infection in Hospitals-overview A. M. Emmerson”,

Survey of of the results

J. E. Enstone”, M. Griffin?, and E. T. M. Smyths

M. C. Kelsey$

*Department of Microbiology and PHLS, University Hospital, QMC, Nottingham NG72UH, j-Statistics Unit, CPHLS, Colindale, London NW9, $Department of Microbiology, Whittington Hospital, Highgate Hill, London N19 5NF; and $Department of Bacteriology, The Royal Hospitals Trust, Belfast BT126BA, UK Received 10 January

1996; manuscript accepted 25 January

1996

Summary: This study was designed to assess the overall prevalence of infection among patients in hospitals in the UK and the Republic of Ireland. Patient data were collected and entered directly into a portable Olivetti (Xl 2 notebook) computer with a custom-designed program (Epi-Info version 5.01). The statistical analysis was performed using the Statistical Package for Social Sciences software (SPSS). I n all, 37 111 patients from 157 centres were studied, and a mean hospital acquired infection (HAI) prevalence rate of 9.0% (range 2-29X) was calculated. HA1 rates were higher in teaching hospitals (11.2%) than in non-teaching hospitals (8.4%) P
data

Prevalence collection.

survey;

hospital-acquired

infections;

computer-

Introduction The Second National Prevalence Survey was designed to assessthe overall prevalence of infection of patients in hospitals in the UK and the Republic of Ireland together with their associated risk factors and sites of infection, using agreed definitions of infection’ and a computer-assisted questionnaire.* Although there is a natural tendency to compare the results of the second study performed in 1993-1994 with the first study carried out in England and Wales in 1980, there are many differences.’ During this period there have been many changes in medical practice that have caused hospitalacquired infections (HAIs) to alter. Although there has been a great improvement in the numbers of properly trained infection control staff, resources allocated to infection control have Correspondence

to:

Professor

A. 51.

Emmerson

176

A. M. Emmerson

et al.

been constrained. Alternatives to hospitalization are available; the duration of hospital stay is shorter and the use of prophylactic antibiotics now exceeds their therapeutic use. On the other hand, hospital resources have had to cope with an ever-increasing ageing population, the expanding transplantation programme and more adventurous surgery. Escalating medical costs over the last five years and the introduction of day-care surgery have resulted in shorter hospital stays and higher volumes of outpatient surgical procedures, thus falsely masking true surgical infection rates. A number of recent studies have highlighted this problem and Byrne et ~1.~ found that with careful post-discharge surveillance and attention to definitions of infection some 60% of post-operative wound infections occurred after discharge. Hospital-acquired infection rates can also be distorted if the method of detection has a low sensitivity and specificity. Surveillance is an essential component for the prevention of infection in hospitals and consists of the routine collection, tabulation, analysis and dissemination of information on HAIs.’ This requires the full utilization of existing sources of information supplemented by periodic surveys. Unfortunately, the information available in hospital patients’ notes is rudimentary, and often incomplete. Data collection is the most timeconstraining element of surveillance, and selective surveillance is the only realistic method for small infection control teams (ICTs). Computerized data collection and analysis of surveillance information has greatly assisted staff in both small and large surveys2 and recent studies in Norway in 1991 ,6 Spain 1991 ,7 Belgium 1991,’ and Belgium and the Netherlands 1992,9 have illustrated the in-depth analyses that can be performed. However, there still seems to be a delay between the study period and publication. Information should be fed back without too much delay and new rapid data collection and analysis systems are needed.” Although the quality of information collected from prevalence surveys lacks the completeness of incidence surveys, the information is nevertheless of value. There exists a general relationship between the two types of survey which depends on the duration of illness.” Thus either can be used to assessthe impact of infection control programmes.‘2 This paper is the first in a series of papers that describes the principal outcome of the second national prevalence survey in the UK and the Republic of Ireland, 1993-l 994. Methods

The methodology used in the second national prevalence survey has been published in detail.2 The study was performed over a 15-month period between May 1993 and July 1994 in two-month study periods. Patient data was collected at the bedside and entered directly onto a portable Olivetti (Al2 notebook) computer using a custom-designed program (Epi-Info Version 5.01).

National

Prevalence

Survey:

overview

177

0 50

150

250

350

450

Number ITigure surveyed.

1, Distribution

of the

Table Hospital

no hospital

of patients

Number

associated

650

surveyed

I. Numher of hospitals/patients

type

District general Teaching/university Others None* Total * Where

number

550

750

of patients

of hospitals 103 46 8

(65.6) (29.3) (5.1)

157 (100~0)

in each

of the

157

hospitals

by type of hospital (‘K)

Number

of patients

(‘X,)

23 592 (63.6) 12 287 (33-1) 1001 (2.7) 231 (0.6) 37 111 (100.0)

type was provided

On completion of the study at each of the 157 centres, the data was transferred on disk to the study co-ordination centre and reviewed for obvious errors, inconsistencies and omissions. The data was then subjected to a computerized validation and error detection program. A preliminary report and a list of queries regarding specific patients was then produced and forwarded to the originating centre. The amended data was then forwarded to the Statistics Unit, Central Public Health Laboratory, Colindale, where the results from all centres were merged. The statistical analysis was performed on a computer running the Statistical Package for Social Sciences software (SPSS Inc., Chicago, Illinois, USA). Results

One hundred and fifty-seven hospitals completed a survey of their hospital beds and collected data on 37 111 patients. The distribution of the number of patients entered into the study by each centre is shown in Figure 1. The number surveyed per hospital ranged between 11 and 781 (median 239).

A. M. Emmerson et al.

178 Acute medicine General surgery’; OrthopaedicYB-auma Gynaecology Cardiothoracic surgery Healthcare of the elderly Acute chest Burns/Plastics Maxillary/Facial Ears, nose and throat Eye Skin Intensive care Coronary care HaematologylOncology Maternity/Newborn SCBU Paediatrics NeurologyiNeurosurgery UrologyKJrosurgery Infectious diseases 0

6

10

16

Figure 2. Comparison between the national distribution of beds by distribution among patients surveyed. (I%!), actual; ( q ), target. * Includes Psychiatric and dental patients not illustrated.

20 speciality vascular

J

26

and the surgery.

The hospitals were divided into the following types, district general (DGH), teaching, university associated, private sector, community, specialist/special hospital authority and armed forces. For the purposes of analysis, these have been grouped into DGH, teaching/university associated and others. The proportion of each hospital type included in the study is given in Table I. Almost two-thirds (103 of 157) of the hospitals surveyed were district general hospitals whereas teaching/university associated hospitals made up four-fifths (46 of 53) of the remainder. The beds surveyed as a reflection of the declared national bed distribution (UK and the Republic of Ireland) is shown in Figure 2. Twenty-three specialities (excluding psychiatry) were surveyed and the sample size shows close proximity to those beds available for the study. General medicine, general surgery, (including vascular surgery) healthcare of the elderly, maternity, and orthopaedic/trauma comprised 60% of the total surveyed. Table II illustrates the number of patients surveyed according to age, sex and the consultant speciality under which they were being treated. Psychiatric beds are included for completeness, although it was not intended to survey this speciality. Maternity includes newborn infants. The overall total excludes 297 patients (0.03%) for whom no speciality was provided. It should be noted that 30% (11 159 of 36 809) of patients were over 75 years of age. Certainty in the diagnoses of infection within the categories ‘certain’, ‘probable’ and ‘possible’ varied with the infection concerned as shown in

speciality

* included Xl, male;

for completeness. F, female; SCBL,

Acute medicine General surgery \7ascular surgery Orthopaedic/trauma Gynaecology Cardiothoracic surgery Healthcare of the elderly Acute chest Burns/plastics Maxillary/facial Ears, nose and throat Eye Skin Intensive care Coronary care Haematology/oncologq Maternity/new-born SCBU Paediatrics Neurology/neurosurgery Urology/urosurgery Infectious diseases Dental Psychratrn? Total

Consultant

speed

Table

<1

140

130 38:

91 91

5, : 37: 140 438 1 286 541 3 8

care baby

unit.

169 x 0 123

54 52 149 53

49 15 142

52 30

>65-~75 M F

they

M

were

>75

being

F

treated

182 13 0 0 123

47 36 43 55

:t8 88

26

109 i 1 42

27 77 44 98

118 86

302 76

1010 0 0 45

87 42 20 65

223 56

570 0 2 21

32 99 21 38

208 57

X80 0 0 16

234 77 10 35

314 46

273 49 1337 43 2272 46

977 1421 1204 1110 1544 660 67X 524 588 741 28 93 32 55 53 385 281 550 401 1345 450 0 138 0 121 43 91 41 24 15

>44-<65 M F

which

: 92 98 37 255 63 40 15 372 94 19 59 423 10 78 18 2 11 15 1 3 0 :, 0 1 0 19 15 6 9 8 26 11 27 565 2546 4756 3915 3374 3X44 3343 4357 6802

6

42 20 218

43 32 174

311

under

and sex

554 1428 435 688 2 53 276 402 705 1 8 153

1320 2033 109 0 0 48 54 120 78

ii

21 72 206

i 50

55

2

262

535 416 7 568 1 26

>14-144 M F

h0

2

:

5 18 0 45 0

14 F

4 24 0 63 0

>l-5 M

Age groups

by age, sex and speciality

12 7 0 11 9 1

F

surveyed

360 3 4 4 ; 100 0 0 0 u 0 0 13X5 1161 761

M

II. Patients

4503 239X 208 1727 2 296 1673 199 174 52 548 271 165 166 318 482 409 565 952 317 1162 165 12 44 16808

M -

F

% 20001

4;: 407 197 100 167 495 2422 439 729 271 297 82

4296 2385 115 2612 1423 109 2572 182 140

All ages

8799 4783 323 4339 1425 405 4245 381 314 99 964 678 362 266 485 977 2831 1004 1681 588 1459 247 33 121 36809

Total

180 Upper

A. M. respiratory

et al.

Emmerson

tract

Intra-abdominal Gastro-intestinal tract Reproductive tract Central

nervous

system

Lower

Urinary respiratory Surgical

Bone tract tract wound -. Skin

I 40

0

Percentage Figure 3. The ( q ), certain.

degrees

of certainty

in the diagnosis

60 certainty

of infection.

( n ), possible;

(a),

probable;

Figure 3. Infections where the number of cases exceeded 100 are illustrated. The distribution of the number of HAIs and community-acquired infections (CAIs) diagnosed in each of the 157 hospitals are shown in Figures 4(a) and 4(b). Th e overall mean HA1 for the 157 centres was 9.0% with a range of 2-29% with one outlier of 54.5% (this centre surveyed 11 beds only before withdrawing from the study). Although the prevalence survey concentrated on HAIs, CAIs were included. Table III compares HA1 and CA1 between the 19803 and 1994 studies. Table IV(a) compares the prevalence of HA1 amongst the different hospital types. District general hospitals showed a prevalence of 8.2% compared with 10.7% associated with teaching/university associated hospitals. However a sub-analysis, shown in Table IV(b), demonstrates a significant difference between teaching (11.2%) and non-teaching (8.4%). Table V compares the 1980 and 1994 surveys of the four major groups of HA1 with the total numbers, means and confidence intervals. The distribution of HA1 by speciality, comparing 1980 with 1994, is listed in Table VI. Haematology/oncology and intensive care, plus others, were not recorded as separate specialities in the 1980 study. Table VII lists HA1 according to the system affected; CAIs are shown for comparison. The four major sites of infection; infections of the urinary tract (UTI), lower-respiratory tract, surgical wound and the skin are the same as those in the 1980 study but the order of prevalence is different when compared with CAI. The prevalence of the four major HAIs by age and sex are shown on Table VIII. CAIs are included for comparison. Table IX(a) compares HA1 and CA1 for the four major types of infection

National

2

6

Prevalence

9

13

17

21

Survey:

24

28

32

Percentage

overview

36

39

43

181

47

51

54

5X

50

54

58

of HA1

(b)

,--I

2

6

10

14

18

22

26

30

Percentage

34

38

42

46

of CA1

Figure 4. The distribution of the number of cases percent of (a) hospital-acquired infections (HAI) and (b) community-acquired infections (CAI) diagnosed in each of the 157 hospitals (a normal curve has been superimposed).

Table

I I I. PreP:alence Prevalence 1980

HA1 CA1 H.41, hospital-acquired CXI, community-acquired

o,f infection of infection (‘X,) 1994

9.2 9.9

9.0 14.7 infectlon. infection.

and lists the percentage of patients in each of 24 specialities; Table IX(b) represents a further eight infections where the prevalence of HA1 or CA1 is greater than 0.25%. Table X gives the percentage prevralence of the types of infection distributed by age and sex, and by whether they were HA1 or CAI. The four major infections are presented.

182 Table

Hospital

et al.

A. M. Emmerson IV(a).

Prevalence

(%)

of hospital-acquired hospital types

type

infection surveyed

HA1

District general Teaching/university Others None Total

IV(b). (HAI)

Prevalence in teaching

HA1

1014 8076 9090

x2 63.612;

Infection

obtained

of patients

the various

surveyed

23 592 12 287 1001 231 37 111

of hospital-acquired non-teaching hospitals

(11.2) (88.8) (100.0)

from

infection

Non-teaching

Total

2331 25460 27791

3345 33536 36881

(8.4) (91.6) (lOO*O)

RO.001.

V. Main

hospital

acquired

site

infections,

1980

compared

1980

Urinary tract No. of infections Prevalence* Lower respiratory No. of infections Prevalence* Surgical wound No. of infections Prevalence* Skin No. of infections Prevalence* Total HA1 No. of patients Prevalence* * Confidence

(%) and

Teaching

Yes No Total

Table

Number

1943 (8.2) 1320 (10.7) 82 (8.2) 8 (3.5) 3353 (9.0)

associated

Table

(HAI)

intervals

with

1994

1994

2.79

506 (2.56-3.03)

2.41

894 (2.26-2.57)

I.55

281 (1.37-1.73)

2.38

882 (2.22-2.53)

I.78

324 (1.59-1.98)

1.11

413 (1.0 -1.22)

I.24

225 (1.08-I

I.00

370 (0~90-1~10)

9.20

1671 (8.78-9.62)

9.03

3353 (8.74-9.32)

tract

given

.40)

in brackets.

Discussion

The First National UK Prevalence Survey of infection in 43 hospitals throughout England and Wales was conducted in 1980,3 and identified four major groups of HAI: UT1 (30*3%), surgical wound (18.9%), lowerrespiratory tract (16.8%) and skin infections (13.5%). The overall prevalence of HA1 was 9.2%. The present study was conducted 15 years after the first survey and included patients in 157 hospitals throughout England, Wales,

National Table

VI.

Prevalence

Consultant

Prevalence of hospital

* .Uot specified

acquired infection with 1994 1980

speciality

Acute medicine General surgery Vascular surgery* Orthopaedic/trauma Gynaecology Cardiothoracic surgery? Healthcare of the elder11 Acute chestt Burns/plastics* Maxillary/facial* Ears, nose and throat Eye Skin$ Intensive care$ Coronary care$ Haematology/oncology* Maternity/newborn SCBU Paediatrics Neurology/neurosurgeryt Urology/urosurgery Infectious diseasest Dental* Psychiatricg Overall prevalence

f Included

Survey:

(N=1671) 7.6 12-1 13.1 11.0 10.1

6.3 2.1

4.4 16.8 4.1 16.1

9.2

overview

183

by speciality,

1994

1980 compared

(N=3338) 8.1 9.8 16.7 11.4 10.6 11.8 10.0 3.9 15.9 7.1 4.4 1.5 7.2 34.2 7.2 16.3 24 14.2 5.6 14-t 9.7 6.5 0.0 2 5 9.0

in 1980.

in General

Surgery

1980.

$ Included in Acute Rledicine 1980 5 Included for completeness. SCBU, special care baby unit.

Scotland and all Ireland. The same four major groups of infection were identified; UT1 (23.2X), surgical wound (10*7%), lower-respiratory tract (22.9%) and skin infections (9.6%). The mean overall prevalence of HA1 was similar at 9.0%. The most significant change during this period seems to be the fall in surgical wound infections from 18.9% to 12.3%. There are a number of reasons why this may be so, not least the immense improvement in surgical technique, bowel preparation and the widespread use of prophylactic antibiotics. The 1980 study included accidental wounds in the surgical wound group. The length of stay in hospitals nowadays is much shorter than it was in 1980 and, therefore, it is likely that more surgical wound infections will become apparent after hospital discharge.‘The impact of antibiotic use will be published at a later date. The large increase in lower-respiratory tract infections from 16.8% in 1980 to 22.9% in 1994 may in part be a result of the fact that the survey covered 15 months and there was a high rate of respiratory infection in the

184

A. M. Table

VII.

Infection

Infections

et al.

Emmerson

in hospital patients according a percentage of all infections

site

to the system

HA1

Skin Surgical wound Lower respiratory tract Intra-abdominal Burns CAPD Central nervous system Ear Eye Gastrointestinal Peripheral device Central line Other vascular device Bone Undiagnosed fever Implant Urinary tract Wound drain site Reproductive tract Septicaemia Upper respiratory tract

Table

hospital-acquired ambulatory

VIII.

Prevalence

15

54 186 46 894 20 34 239 76 3848

infection; CAI, peritoneal dialysis.

of the four

main

Infection O-51 M CAI* HA1 Urinary Surgical Lower tract Skin

tract wound respiratory

hospital-acquired

infection;

infections

CAPD,

(HAI)

10.6 4.6 I.0 0.8

13.7 9.1 I.7 I.5

12.1 9.9 3.1 I.5

I.2 0.5

2.2 0.8

0.6 0.5

2.9 0.7

2.0 I.2

25.6 4.2 0.9 0.3

2.1 I.2

I.5 1.7

0.9 0.5

male;

A:: 0.2 2.3 3.1 0.5 14.2 0.0 I.9 4.0 4.6 100

2 112 236 269 5894

17.5 8.2 0.8 I.0

7.8 8.4 0.3 0.2

3K 4.1 I.1 0.3 I.6 0.8 1.9 4.9

3; 10 135 183

28.1 5.8 I.4 0.5

10.7 8.5 0.4 0.2

15.4

1; 94 48 111 287

>65-<75 M

F

M,

community-acquired

909 42 2282 244

and sex >44-165 M F

14 F

infection;

9.6 10.7 22.9 2.4 0.6 0.3 0.6 0.3 3.0 4.9 1.9 2.0 0.4 I.4 4.8 I.2 23.2 0.5 0.9 6.2 2.0 100

Age (years) >14-544 M F

>l-2 M

* Included for comparison. CAI, community-acquired

Count

370 413 882 93 22 13 23 11 116 189 75 77

Total

as

CA1

Count

HAI, tinuous

affected,

con-

by age and

sex

>75 F

M

F

16.6 10.3 2.3 I.4

14.5 9.7 2.7 1.3

17.6 11.2 3.3 I.1

15.6 IO.8 4.4 I.2

3.4 I.2

2.9 I.0

3.7 1.1

2.4 I.2

F, female.

community. The clinical interpretation of chest infections is difficult (degree of certainty only 3 1o/o) in spite of improved definitions of infection and new diagnostic tests such as bronchoalveolar lavage. The highest rates of lowerrespiratory tract infection were in patients in intensive-care units (21.8%) and in male patients over 75 years of age.

?‘he

speciality

IXa.

preralenre

* Included

for completeness.

Acute medicine General surgery Vascular surgery Orthopaedic/trauma Gynaecology Cardiothoracic surgery Healthcare of the elderly Acute chest Burns/plastics Maxillary/facial Ears, nose and throat Eye Skin Intensive care Coronary care Haematology/oncology Maternity/newborn SCBU Paediatrics Neurology/neurosurgery Urolog~/Llrosurgerv Infectious diseasesDental Psychiatric* No. of cases Prevalence (‘%I)

Consultant

‘rable

8810 4797 323 4344 1425 406 4246 381 314 99 964 678 362 266 486 977 2837 1007 1619 589 1460 247 33 121 36791

Number surveyed

of commzu~ity-

22.0 11.6 9.3 6.6 5.2 2.2 19.9 44.4 4.8 11.1 12.3 6.2 24.6 21.1 7.6 16.3 3.5 14.2 31.7 4.8 10.8 65.6 3.0 4.1 5444 14.80

CA1

((‘ill) X11

ad

8.1 9.8 16.7 11.4 10.6 11.8 10.0 3.9 15.9 7.1 4.4 1.5 7.2 43.2 7.2 16.3 2.4 14.2 5.6 14.4 9.7 6.5 0.0 2.5 3338 9.07

HA1

2.6 0.2 0.5 2.3 0.2 0.6 8.1 0.0 0.8 909 2.47

;:;

3.3 3.0 7.7 2.1 0.3 0.0 34 1.8 3.2 5.1 1.2 0.6 22.4

CA1

Irospitnl-ncqlliv&

Skin

0.9 0.X 2.8 1.4 0.3 0.7 1.3 0.8 3.2 1 .o 0.6 0.0 3.9 1.1 0.8 1.5 (I,4 2.6 0.5 0.7 0.5 1.2 0.0 0.8 367 1 .oo

HAI

infwtiom

0.3 0.0 0.0 0.1 0.0 0.0 0.0 0.2 0.1 0.0 0.0 0.0 42 0.11

;:A

0.0 0.3 0.9 0.4 0.1 0.2 0.0 0.0 0.0 0.0

CA1

Wound

(HAI)

0.2 2.4 6.2 2.8 2.4 2.5 0.3 0.3 3.5 2.0 1.9 0.0 1.4 2.3 0.6 0.1 0.4 0.1 0.7 1.5 0.8 0.0 0.0 0.0 413 1.12

HA1

(percent

in

12.8 0.9 0.6 1.0 0.3 1.0 11.8 40.4 0.3 0.0 1.2 0.4 0.3 12.8 3.9 4.4 o-4 0.7 11.9 0.3 0.8 21.9 0.0 1.7 2282 6.20

2.5 2.6 4.6 2.0 1.0 4.4 3.3 1.6 1.6 2.0 1.5 0.1 1.4 21.8 3.3 3.9 0.2 3.0 1.1 7.1 1.2 1.2 0.0 0.0 881 2.39

respiratory tract CL41 HAI

Lower

of patient.7

each

;:; 0.X 839 2.28

2.7 1.9 0.0 1 .o 1.4 0.0 4.5 2.1 0.0 1.0 0.3 0.8 0.8 0.8 0.6 1.1 1.7 0.2 3.1 0.3 7.5

CA1

Urinary

speciality)

2.6 1.9 0.6 3.7 5.1 1.0 3.6 0.5 1 .o 1.0 0.4 0.6 0.0 3.0 1.2 1.5 0.2 0.5 0.8 2.9 6.1 0.4 0.0 0.8 894 2.43

HAI

tract

* Included

for completeness.

(%)

CNS,

36791

Prevalence

of cases

No.

Number surveyed

distribution

8810 4797 323 4344 1425 406 4246 381 314 99 964 678 362 266 486 977 2837 1007 1619 589 1460 247 33 121

speciality

The

Acute medicine General surgery Vascular surgery Orthopaedic/trauma Gynaecology Cardiothoracic surgery Healthcare of the elderly Acute chest Burns/plastics Maxillary/facial Ears, nose and throat Eye Skin Intensive care Coronary care Haematologyjoncology Maternity/newborn SCBU Paediatrics Neurology/neurosurgery Urology/urosurgery Infectious diseases Dental Psychiatric*

Consultant

Table IXb.

central

14.80

5444

22.0 11.6 9.3 6.6 5.2 2.2 19.9 44.4 4.8 11.1 12.3 6.2 24.6 21.1 7.6 16.3 3.5 14.2 31.7 4.8 10.8 65.6 3.0 4.1

CA1

All

(CAI)

0.66

244

0.5 3.2 0.3 0.0 0.6 0.2 0.2 0.0 0.0 0.0 0.0 0.3 0.0 2.6 0.0 0.0 0.1 0.0 0.5 0.0 0.3 2.0 0.0 0.0

system;

0.25

93

0.1 1.0 0.3 0.0 0.8 0.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 3.0 0.2 0.1 0.0 0.3 0.3 0.0 0.1 0.0 0.0 0.0

HAI

Intraabdommal CA1

newms

9.07

3338

8.1 9.8 16.7 11.4 10.6 11.8 10.0 3.9 15.9 7.1 4.4 1.5 7.2 34.2 7.2 16.3 2.4 14.2 5.6 14.4 9.7 6.5 0.0 2.5

HAI

of community-

GI,

0.26

94

0.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.2 0.0 0.3 0.3 1.2 0.0 0.0 0.0 0.0

CA1

0.06

0

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3 0.3 2.2 0.0 0.0 0.0 0.0

HAI

0.30

111

0.2 0.1 0.0 0.2 0.0 0.0 0.4 0.0 0.0 1.0 0.0 4.0 0.0 0.0 0.0 0.3 0.1 0.1 0.8 0.2 0.1 4.9 0.0 0.8

CA1

EW

gastrointestinal;

CNS

0.32

116

0.2 0.1 0.3 0.1 0.0 0.0 0.6 0.0 0.0 0.0 0.0 1.3 0.3 1.1 0.2 0.3 0.4 2.1 0.3 0.7 0.0 0.0 0.0 0.0

HA1

and hospital-acquired

SCBU,

0.78

287

0.7 1.2 0.0 0.0 0.5 0.0 0.5 0.8 0.0 0.0 0.1 0.3 0.0 0.4 0.0 1.2 0.3 0.0 3.7 0.2 0.0 18.6 0.0 0.0

CA1

GI

special

0.51

189

0.7 0.5 0.6 0.2 0.1 0.2 0.9 0.3 0.0 0.0 0.1 0.0 0.0 1.1 0.2 1.5 0.0 0.8 0.7 0.5 0.1 3.2 0.0 0.8

HA1

tract

infections

0.14

53

0.0 0.0 0.3 0.9 0.0 0.0 0.1 0.0 0.6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.1 0.0 0.0 0.0

HA1

care baby

0.37

135

0.3 0.1 0.0 1.5 0.0 0.0 0.2 0.0 0.3 1.0 0.0 0.0 0.0 0.4 0.0 0.2 0.0 0.0 0.5 1.7 0.0 1.6 3.0 0.0

CAI

Bone

(HAI)

unit

0.49

182

0.9 0.3 0.0 @l 0.0 0.0 0.1 0.0 0.0 0.0 0.1 0.0 0.3 1.1 0.2 3.5 0.2 0.2 1.3 0.0 0.1 4.9 0.0 0.0 0.50

185

0.3 0.6 0.3 0.3 1.0 1.7 0.3 0.3 0.3 0.0 0.1 0.0 0.0 1.5 0.6 3.9 0.4 0.9 0.4 0.5 0.3 0.4 0.0 0.0

Undiagnosed fever CA1 HA1

(percent

0.30

112

0.1 0.5 0.0 0.0 2.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.6 0.4 0.0 0.2 0.5 0.0 0.1 0.0 1.1 1.2 0.0 0.0 0.09

34

0.0 0.0 0.0 O-1 0.8 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.5 0.0 0.1 0.0 0.0 0.0 0.0 0.0

Reproductive tract CA1 HA1

of patients

0.64

235

1.2 0.4 0.0 0.1 0.1 0.5 0.6 1.3 0.0 0.0 0.0 0.0 0.0 3.4 2.3 1.5 0.1 0.4 1.1 0.3 0.6 1.6 0.0 0.0

CA1

0.65

238

0.6 0.7 1.9 0.2 0.8 0.5 0.2 0.3 0.3 0.0 0.4 0.0 0.3 4.5 0.4 2.0 0.1 5.2 0.8 0.5 0.9 0.0 0.0 0.0

HA1

Septicaemia

76 0.21

267 0.73

F

z

:

0.0

B

g

2.0 0.4

0.0 1.1 0.0 0.1 0.4 0.2 0.1 0.0 0.0 0.8

s m

0.3 0.3 0.0

0.8 0.3

?

0.2 0.2 0.0 0.0 0.0 0.0

0.3 0.1 0.0 0.1 0.0 0.0 0.1 0.8 0.0 3.0 7.2 0.4 0.6 1.1 0.0 1.1 0.0 0.0 8.9 0.2 0.0 5.3 0.0 0.0

Upper respiratory tract CA1 HA1

in each speciality)

National

Prevalence

Survey:

overview

187

188

A. M. Emmerson

et al.

There was a fall in UT1 from 30.3% in 1980 to 26.8% in 1994 but this is barely significant (see Table V). The highest prevalence was in urosurgical (6.1%) and gynaecology (S.lO/o) patients, particularly in women over 75 years of age. It is difficult to compare the results of the 1980 and 1994 surveys even if the discussion is restricted to the four major sites of infection. Without doubt there have been many changes in medical practice, hospital management and patient characteristics of an ageing population. In Europe, there have only been two national prevalence surveys of all infections since 1990, the Epine Study in Spain in 1990’ and the Norwegian survey in 1991 .6 Although the overall prevalence of HA1 in Spain was 9*9%, and that of the UK and Republic of Ireland 9.0%, it would be wrong to compare these figures without a detailed analysis of the patient demography and the medical practices in these two countries. What is more important is to work at repeated prevalence surveys in relation to the infection control practices. This is best illustrated by the study of French et ~1.‘~ who repeated whole hospital surveys at six-monthly intervals and then intervened with effective infection control policies. The second survey in Europe since 1990 is that from Norway by Aavitsland et al. in 1991 .6 This study also used computer analysis using WHO/CDC Epi-Info software, although clinicians were requested to complete forms. This study is interesting in that the overall prevalence rate of HA1 was 6*3%, which is the lowest figure in Europe over the last 20 years. What is more important is that the trend in Norway has dropped from 9.0% in 197914 through 7.8% in 1985lj to 6.3% in 1991.6 As with the study by French et ~1.‘~ the major impact was the large decrease in the prevalence of UT1 infection. The prevalence rate of HA1 in several European countries varies between 6-l 0%6-9 with UT1 accounting for 253.5%, respiratory-tract infection 20-25%, and surgical wound infections 1S-20%. Differences in methodology call for great care in comparing prevalence rates from different countries. The distribution of the number of beds sampled in the 157 hospitals is shown in Figure 1. The median number of beds per hospital surveyed was 239 (range 11-781) w h’ic h is much less than the average of 423 in the 1980 survey. Acute hospitals are smaller in size these days, and although four times as many hospitals were included in the 1994 survey compared with the 1980 survey, only twice as many patients were included. In both surveys it was the intention to only include acute services but 121 psychiatric patients were inadvertently surveyed and have been included in the analysis. In the 1980 survey, each hospital was asked to survey up to 500 patients to avoid overburdening individual contributors. In the 1994 study, all those hospitals that wished to participate in the survey were encouraged to take part, which included some very small specialized hospitals. In this study, most small hospitals surveyed all their beds, whereas larger hospitals were only asked to sample a percentage, thus introducing some bias.

National

Prevalence

Survey:

overview

189

The agreement between the beds declared and beds surveyed illustrated in Figure 2 is not as close as that found in the 1980 survey. One difficulty encountered in this survey was the lack of accurate figures on hospital bed state nationally. On the day of the survey, each hospital had accurate figures of the bed state but at the planning stage this information was not available. Participants in the survey were surprised to find that beds were ‘missing’, either closed, unavailable for use, or amalgamated into other disciplines. The percentages of the five large groups i.e. general medicine, surgery, care of the elderly, maternity and newborn and orthopaedics/trauma (72% of total beds) was similar for all responding centres (189) and participating centres (157) in this second survey and bears a close prosimation to those of the first national survey. The patients surveyed vvere divided by age, sex and speciality and are listed in Table I I. The most striking change since the 1980 survey has been the increased age of both male and female patients. In 1980, 37.7% of males and 40.8% of females vvere 65 years or over. In this survey, the figure has risen to 48.8% for males and 50.7% for females. In total, 30% of all patients in the acute hospitals surveyed were 75 years or older and were not confined to wards designated for care of the elderly-. It is surprising that the degrees of certainty of identifying infections in this study (HA1 certainty of diagnosis =47X) are much less than in the 1980 study (HA1 certainty of diagnosis = 60%). In both surveys, ICTs were trained centrally and all teams worked to agreed definitions. Although the definitions used in this survey’ were more clearly defined, they did in fact follow the mainstream definitions used in 1980. Prevalence surveys are spot-checks of patient infections and use information available at the time of the survey. Incidence surveys would pick up more laboratory reports and should strengthen the degree of certainty of the diagnosis. The values for the percentage prevalence of HA1 and CA1 in each of the participating hospitals seen in Figures 4(a) and 4(b) show a slightly skewed distribution curve for HA1 but a good approximation to a normal distribution for CAI. As with most studies the mean infection rates are quoted but the range of HA1 is lost in the morass of figures. In this survey the mean HA1 rate was 9.03% (95% CI 8.74-9.32) but the range was from O-29’%. In the Epine study’ 26.8% of the hospitals had HA1 prevalence below 7% and in 5 1% of hospitals the HA1 prevalence rate was over 9%. In the Norwegian study” the HA1 prevalence rate was 6.3% but ranged from O-15’%. HA1 prevalence rates do vary between regional and local hospitals, but the highest infection rates are found in intensive-care unit patients who have the highest risk factors (see Table VI). Crude ovTeral1 HA1 rates for hospitals do not allow inter-hospital comparison unless patients are stratified for risk factors such as device-associated infections.‘” Although the four major groups of infection have been discussed, some of the less frequent infections are worth a mention. In 1980, only 18 cases of bacteraemia were documented i.e. 0.1% of the total. In this survey 235

190

A. M. Emmerson

et al.

cases of bacteraemia were documented i.e. 0.63% of the total. This is a large increase and may be a reflection of the severity of illness of hospitalized patients or a reflection of increased clinical awareness and improved blood culture techniques. Similarly infection of the gastrointestinal tract rose from 23 (0.13%) to 189 (0.51%) possibly reflecting ward outbreaks of Clostridium difficile or rotavirus. Risk factors for infection will be discussed in a subsequent paper. This work was funded by the Hospital Infection Society and a research grant awarded to Professor A. M. Emmerson, on behalf of the Hospital Infection Society, from The Nuffield Provincial Hospitals Trust. We are grateful to Dr Michael Ashley-Miller, Secretary of the trust whose initial support facilitated this study. We are indebted to all the infection control doctors and nurses who participated in the study, and who gave up their time so freely to ensure the success of the study, and to hospital staff for their cooperation.

References of a steering group. National prevalence survey of hospital-acquired infections: 1. Report definitions. J Hosp Infect 1993; 24: 69-76. 2. Emmerson AM, Enstone JE, Kelsey MC. The second National prevalence survey of infection in hospitals: methodology. J Hosp Infect 1995; 30: 7-29. 3. Meers PD, Ayliffe GAJ, Emmerson AM, Leigh DA, Mayon-White RT, Mackintosh CA, Stronge JL. Report on the National Survey of Infection in Hospitals 1980. r Hosp Infect 1981; 2: Suppl I-51. 4. Byrne DJ, Lynch W, Napier A, Davey P, Malek M, Cuschieri A. Wound infection rates: the importance of definition and post-discharge wound surveillance. J Hosp Infect 1994; 26: 37-43. of Health. Hospital Infection Control; guidance on the control of infection 5. Department in hospitals. Prepared by the Hospital Infection Working Group of the Department of Health and Public Health Laboratory Service. BAPS, Lancashire 1995. Aavitsland P, Stormark M, Lystad A. Hospital-acquired infections in Norway. A . national prevalence survey in 1991. S econdJ infect D& 1992; 24: 477-483. EPINE Working Groun. Prevalence of hosuital-acauired infection in Suain. 1 I I d7 Hos~ 1 Infect 1992; 20: ‘i-13. I Mertens R, Jans B, Kurtz X. A computerised nationwide network for nosocomial infections surveillance in Belgium. Infect Control Hosp Epidemiol 1994; 15: 171-179. Mertens R, Van den Berg JM, Veerman-Brenzikofer KLV, Kurz X, Jans B, Klazinga W. International comparison of results of infection surveillance; The Netherlands versus Belgium. Infect Contiol Hosp Epidemiol 1994; 15: 574-580. 10. Smyth ETM, Emmerson AM. Survey of infection in hospital: use of automated data entry system. J Hasp Infect 32: (in press). 11. Wenzel RP, Streed SA. Surveillance and use of computers in hospital infection control. J Hosp Infect 1989; 13: 217-229. 12. Emmerson AM. The impact of surveys on hospital infection. J Hosp Infect 1995; 30: Suppl 421-440. 13. French GL, Wong SL, Cheng ATB, Donnan S. Repeated prevalence surveys for monitorine effectiveness of infection control. Lancet 1989: 2: 1021-1023. 14. Hovig B, Lystad A, Opsjon H. A prevalence survey of infections among hospitalised patients in Norway. Nat1 Inst Pub1 Health Annals 1981; 4: 49-60. 15. Lystad A, Stormark A. A national prevalence survey of hospital acquired infections in Norway. In: Acts from the International Symposium on the Control of Hospital Infection, April 27-29 1987 Rome, Florence: Edizone Riviste Scientific 1987. 16. Working Party Report. Nosocomial infection rates for interhospital comparison: limitations and possible solutions. A report from the NNIS system. Infect Control Hasp Epidemiol 1991; 12: 609-621.