Surveillance of Surgical Site Infection Annual Report For procedures carried out from: January December 2009

Transcription

1 Surveillance of Surgical Site Infection Annual Report For procedures carried out from: January December 2009 Scottish Surveillance of Healthcare Associated Infection Programme (SSHAIP)

2 Contents Acknowledgement 5 Glossary 6 NHS Board participation 7 New developments 7 Key findings 7 Trends in rates of SSI 7 Variation between NHS Boards 7 1. Introduction Using SSI data to inform practice 8 2. Aims and Objectives 9 3. Methods Surveillance methodology Post discharge and readmission surveillance Analysis presented in this report 10 4 Results Procedures Patient demographics Incidence of SSI in Incidence of SSI 2003 to Incidence of SSI by age Characteristics of SSI Inpatient incidence density of SSI, by year of surveillance, 2003 to Incidence of SSI by risk group Readmission Surveillance for hip arthroplasty PDS Surveillance for caesarean section Variation in SSI Rate by NHS board Compliance with guidelines Discussion Conclusions References Appendices 38 Appendix I: SSI rates 38 Appendix II: NNIS Risk Score 38 2

3 List of Figures Figure 1: Infection type by procedure, inpatient SSI 2003 to Figure 2: Infection type by procedure, inpatient SSI Figure 3: SSI rate for deep infection by procedure, inpatient SSI Figure 4: Annual rate of inpatient SSI per 1000 patient days (incidence density) with 95% CI for abdominal hysterectomy, 2003 to Figure 5: Annual rate of inpatient SSI per 1000 patient days (incidence density) with 95% CI for breast surgery, 2003 to Figure 6: Annual rate of inpatient SSI per 1000 patient days (incidence density) with 95% CI for caesarean section, 2003 to Figure 7: Annual rate of inpatient SSI per 1000 patient days (incidence density) with 95% CI for hip arthroplasty, 2003 to Figure 8: Trends in rate of inpatient SSI per 1000 patient days (incidence density) with 95% confidence intervals for knee arthroplasty 20 Figure 9: Trends in rate of inpatient SSI per 1000 patient days (incidence density) with 95% confidence intervals for major vascular surgery 21 Figure 10: Trends in rate of inpatient SSI per 1000 patient days (incidence density) with 95% confidence intervals for open reduction of long bone fracture 21 Figure 11: Method of detection by year for hip arthroplasty to day 30, 2007 to Figure 12: Type of SSI detected in hip arthroplasty by inpatient and readmission surveillance to day 30, Figure 13: Proportion of SSI by method of detection for caesarean sections, 2007 to Figure 14: Cumulative incidence (no of SSI per 100 procedures) of inpatient SSI (NNIS = 0) by NHS board in 2009 for caesarean section procedures (n = 11381) 26 Figure 15: Cumulative incidence (no of SSI per 100 procedures) of SSI rate including inpatient and PDS to day 10 (NNIS = 0) by NHS board from April to December 2009 for caesarean section procedures (n = 8814) 27 Figure 16: Cumulative incidence (no of SSI per 100 procedures) of inpatient SSI (NNIS = 0) by NHS board in 2009 for hip arthroplasty (n = 4294) 28 Figure 17: Cumulative incidence (no of SSI per 100 procedures) of inpatient and readmissions to day 30 SSI (NNIS = 0) by NHS board in 2009 for hip arthroplasty (n = 4294) 28 Figure 18: Cumulative incidence (no of SSI per 100 procedures) of inpatient SSI (NNIS = 0) by NHS board in 2009 for knee arthroplasty (n = 2839) 29 Figure 19: Timing of administration of antibiotic prophylaxis for hip and knee arthroplasty surgery in 2009 (n = 15404) 29 Figure 20: Duration of Prophylactic antibiotics therapy in caesarean sections and orthopaedic surgery in 2009 (n = 30511) 30 Figure 21: Prophylactic antibiotics given in accordance with local guidelines for caesarean section and orthopaedic surgery in 2009 (n = 30511) 31 Figure 22: Antibiotic impregnated cement used for hip and knee arthroplasty in 2009 (n = 12173) 31 Figure 23 : Consultant performing procedure or present within theatre for hip and knee arthroplasty surgery in 2009 (n = 16012) 32 Figure 24: Administration of venous thromboembolism prophylaxis for orthopaedic surgery in 2009 (n = 16012) 3 32

4 List of Tables Table 1: Annual number of operations by procedure category 12 Table 2: Median age and proportion of female patients by procedure category 2003 to 2009 and Table 3: Number of participating boards, procedures, inpatient SSI and inpatient cumulative SSI incidence rate by procedure, Table 4: Number of patient days, inpatient SSI and inpatient SSI incidence density SSI per 1000 post operative inpatient days, by category of procedure, Table 5: Number of procedures, inpatient SSI and inpatient cumulative incidence SSI rate by procedure, 2003 to Table 6: Incidence density of inpatient SSI per 1000 post operative inpatient days with 95% confidence interval, by category of procedure, 2003 to Table 7: Cumulative incidence of inpatient SSI, by category of surgical procedure, by NNIS risk index for, 2003 to 2009 and Table 8: Number of procedures, SSI and rate of SSI by hip arthoplasty subcategory 2007 to Table 9: Number of procedures, SSI and rate of SSI by hip arthoplasty subcategory for

5 Acknowledgement The Surgical Site Infection (SSI) surveillance staff, throughout NHS boards, are to be commended for their efforts dedicated to collecting and reporting SSI data to Health Protection Scotland (HPS). Thanks are also extended to the members of the Scottish Surveillance of Healthcare Associated Infection Programme (SSHAIP) team who have contributed to this report and the SSI programme of surveillance in order to make a difference to the care surgical patients receive in NHS Scotland. 5

6 Glossary ASA AA BR CABG CEL DG ECDC ECOSS FF FV GR GGC HAI HDL HPA HPS HG ICTs LN LO NHS NNIS NW OPCS4 PDS SAPG SIGN SSHAIP SSI SSIRS TY American Society of Anesthesiologists Ayrshire & Arran Borders Coronary arterial bypass grafts Chief Executive Letter Dumfries & Galloway European Centre for Disease Control Electronic Communication of Surveillance in Scotland Fife Forth Valley Grampian Greater Glasgow & Clyde Healthcare associated infections Health Department Letter Health Protection Agency Health Protection Scotland Highland Infection Control Teams Lanarkshire Lothian National Health Service National Nosocomial Infection Surveillance National Waiting Times Centre Office of Population, Censuses and Surveys Classification of Surgical Operations and Procedures (4th revision) Post discharge surveillance Scottish Antimicrobial Prescribing Group Scottish Intercollegiate Guideline Network Scottish Surveillance of HAI Programme Surgical site infection Surgical site infection reporting system Tayside 6

7 Key Points Surveillance of Surgical Site Infection data for procedures performed between January 2003 and December 2009 NHS Board participation Health Protection Scotland (HPS) continue to facilitate national surveillance of surgical site infection (SSI). All 15 of the NHS boards in Scotland participated in the SSI programme in the seventh year (2009). In the last year, 2009, 235 inpatient SSI resulting from procedures have been reported to HPS. In the seven complete years the surveillance has been performed (2003 to 2009) 1695 inpatient SSI, resulting from procedures, have been reported to HPS. New developments Since April 2009, NHS boards have been required to undertake post discharge surveillance, until day 10 post operatively, for all caesarean section procedures performed. Key findings The incidence of SSI increased with the number of risk factors present for the categories of surgery where there were sufficient data to perform these analyses. The incidence of inpatient SSI varied by surgical category. Inpatient SSI rates ranged from 0.3% for knee arthroplasty to 4.7% for coronary arterial bypass grafts (CABG) during The results from the surveillance have been used by NHS boards at a local level to review clinical practice and have resulted in improvements in performance, both in terms of the process of care (e.g. antibiotic prophylaxis compliance) and in terms of outcome (i.e. reduction in SSI rates). Trends in rates of SSI The inpatient SSI incidence density rates in NHS Scotland over the duration of the SSI surveillance programme ( ) showed a significant linear reduction over the seven years of surveillance for breast surgery, knee arthroplasty, major vascular surgery and open reduction of long bone fractures. The inpatient SSI incidence density rates in NHS Scotland showed a significant reduction in caesarean sections over the three years ( ) since surveillance of this procedure was made mandatory. Variation between NHS Boards The incidence of SSI varied by NHS board performing the surgery. This variation may be attributable to the number of procedures performed, case mix of the patient population and length of stay variations. 7

8 1. Introduction Surgical site infection (SSI) is one of the most common healthcare associated infections (HAI), estimated to account for 15.9% of inpatient HAI 1. The risk of SSI following surgery varies according to the procedure carried out 2, within NHS Scotland inpatient SSI rates varied from 0.2% in knee arthroplasty to 6.6% in coronary arterial bypass grafts (CABG) 3 in 2008 and in NHS England SSI rates varied from 0.3% for knee prosthesis and cholecsystemectomy to 9.4% for liver, bile duct and pancreatic surgery 2 from July 2004 to June SSI is the most preventable of all HAI 1;4. SSI cause excess morbidity and mortality and are estimated on average to double the cost of treatment, mainly due to the resultant increase in length of stay 5. In the USA, SSI have been estimated to result in almost one million additional bed days and cost a total of $1.6 billion 6. SSI have serious consequences for patients affected as they can result in pain, suffering and in some cases require additional surgical intervention 7. The impact on the individual can be difficult to quantify, however a recent study 8 found that following a deep SSI, patients experienced pain, isolation, social and economic problems and that these changes can persist for months or years after the surgical procedure. SSI rates are an important surgical outcome measure and the two key aims of SSI surveillance are to provide participating hospitals with robust SSI rates for benchmarking and to use these data to improve the quality of patient care. Evidence suggests that actively feeding back data to clinicians contributes to reductions in rates of infection 9. The average length of stay in NHS Scotland has decreased from 6.0 days in 2004 to 5.3 days in ; this may be due to advances in surgical techniques, the introduction of less invasive procedures and the move towards outpatient and day case treatment. Literature from several countries suggests that between 53% and 84% of SSI may occur following discharge from hospital and as post operative length of stay has decreased more of these infections will occur in the community This trend makes detection of SSI after discharge, or PDS, increasingly important in identifying the true risk of infection following surgery 14;15. In 2001, the Scottish Executive established the requirement for all NHS boards to participate in inpatient SSI surveillance of at least two procedures from a list of ten in the Health Department Letter HDL(2001) Prospective readmission surveillance for hip arthroplasty and PDS for caesarean section procedures for 30 post operative days was made a mandatory requirement in January 2007 through the release of HDL(2006) The period of post discharge surveillance (PDS) for caesarean sections was reduced to ten post operative days from April 2009 by Chief Executive Letter CEL 11 (2009) 18 to improve the consistency of surveillance across NHS boards. 1.1 Using SSI data to inform practice The overarching aim of SSI surveillance is to reduce the incidence of infection following surgical intervention. One factor in achieving this aim is to encourage NHS boards to use their data to evaluate local practice. A quarterly report is produced and distributed by Health Protection Scotland (HPS) to each NHS board showing their results for that quarter broken down by the major reported risk factors for SSI. An electronic reporting tool has been developed within HPS surgical site infection reporting system (SSIRS). This allows stakeholders to examine their SSI data and produce local reports and facilitates boards 8

9 monitoring their rates close to real time. Both these tools can be used to monitor local practice and initiate further investigation and action. In addition to the quarterly reports, supplementary analyses are undertaken by HPS on a quarterly basis to identify any NHS board shown to have a substantial change in SSI rates between two quarters or a higher than expected rate within the quarter. These NHS boards are alerted to this by the production of an individual exception report. NHS boards identified are contacted by HPS to highlight the high rate and are advised to take appropriate action to investigate these changes. An important aspect of SSI surveillance data is to monitor compliance with best practice as defined within clinical guidelines and care bundles as this can assist in reducing infection rates 19. The Scottish Intercollegiate Guideline Network (SIGN) produce evidence based guidelines to promote best clinical practice. SIGN Guideline 104, Antibiotic Prophylaxis in Surgery 20 is aimed at reducing inappropriate prophylactic prescribing and recommends: Intravenous prophylactic antibiotics should be given less than or equal to 30 minutes before the skin is incised. The duration of antibiotic prophylaxis should not be more than 24 hours. Antibiotic impregnated cement is used for cemented joint replacement. SIGN Guideline 62, Prophylaxis of venous thromboembolism 21 recommends: All general, gynaecological or orthopaedic surgery patients should have mechanical and/or chemical prophylaxis. This report will present compliance throughout NHS Scotland with these guidelines. This report presents the results of the analysis of the cumulative data from 2003 to 2009 and on data from Aims and Objectives The aim of this report is to estimate the magnitude of SSI risk in surgical patients in NHS Scotland. The objectives of this report are to: describe the characteristics of patients included in this surveillance programme. present the incidence density SSI rates by surgical procedure in the most recent years of surveillance and over the whole period of surveillance. describe the characteristics of inpatient SSI identified within the surveillance programme. identify trends in incidence density SSI rates over the period 2003 to describe the variation in incidence density SSI rates between NHS boards and highlight boards with unexpectedly high rates. describe the characteristics of SSI identified by post discharge and readmission surveillance since these components of surveillance were made mandatory. assess compliance with SIGN guidelines at a national level including those pertaining to the prevention of surgical site infection and the administration of prophylactic antibiotics. 9

10 3. Methods 3.1 Surveillance methodology Data are collected according to the Scottish Surveillance of HAI Programme (SSHAIP) standardised national protocol 22 to ensure a consistent approach to data collection. The Centers for Disease Control and Prevention case definitions for SSI are used 23. SSI must occur within 30 days of surgery. The procedures included in the surveillance programme are abdominal hysterectomy, breast surgery, CABG, caesarean sections, cardiac surgery, cranial surgery, hip arthroplasty, knee arthroplasty, major vascular surgery and open reduction of long bone fractures. As a minimum, where these procedures are performed, NHS boards must continually collect data on hip arthroplasty and caesarean section procedures, in line with the requirements of HDL (2006) and CEL (11) Post discharge and readmission surveillance For the first time this report contains rates of SSI for caesarean section procedures detected until day 10 post operatively which was made mandatory from the 1st April All NHS boards have established networks with community midwives who routinely monitor caesarean section patients for the first 10 days after surgery and all SSI identified through PDS are reported to HPS. Each NHS board has established methods to identify patients readmitted with an SSI within the first 30 days following a hip arthroplasty procedure; this will identify additional SSI to those found during the inpatient period. The report indicates where caesarean section PDS infections or hip arthroplasty readmission infections are included in analyses and analyses of readmission or PDS SSI will be limited to 2007 to 2009, when surveillance of these procedures was made a mandatory requirement. 3.3 Analysis presented in this report This report includes seven years of SSI surveillance data and describes cumulative data from 2003 to 2009 and the most recent year s data from A total of 15 NHS boards, 14 territorial and one special NHS board participated in the mandatory programme of SSI surveillance. The SSI rates described in this report are presented as cumulative incidence SSI rates (number of SSI/number of procedures*100) or as incidence density SSI rates (number of inpatient SSI/number of inpatient post operative days*1000), used where the length of stay may be a confounding factor (Appendix I). All rates described in this report are inpatient SSI rates unless otherwise stated. Patient days are calculated as the number of days from operation until discharge from hospital. Annual rates are presented as inpatient SSI incidence density rates to allow for changes in the inpatient length of stay from 2003 to 2009 and trends in annual rates are assessed through using the linear by linear association chi-square test. This test examines linear changes over time. 10

11 The National Nosocomial Infection Surveillance (NNIS) risk index was developed in 1991 to enable stratification of infection rates by risk category 24. This index allows benchmarking to be carried out whilst accounting for differences in the distribution of risk factors in comparison patient populations. The NNIS risk index is a method of categorising patients by the major risk factors associated with developing an SSI, i.e. a wound class of contaminated or dirty; an American Society of Anesthesiologists (ASA) physical status classification of three or more and a duration of procedure greater than the time at the 75th percentile (based on US National Nosocomial Infection Surveillance system) indicating a more complex procedure and increased opportunity for microbial contamination of the wound (Appendix II). For each procedure a score of 0 to 3 is allocated to represent the number of risk factors present. Patients with a score of 0 are at the lowest risk of developing an SSI while those with a score of 3 have the greatest risk. The use of this risk index allows for the comparison of similar patient groups in terms of SSI risk over time. Within this report comparison of SSI rates between NHS boards is performed using only procedures with a NNIS score of 0 to eliminate confounding factors included in the NNIS score, however this does not correct for other possible confounding factors. Comparison of NHS boards inpatient cumulative incidence SSI rates for the latest year are made through the production of funnel plots 25;26 and for caesarean section procedures these comparisons are made separately with inpatient rates and rates including PDS surveillance to post operative day 10. In hip arthroplasty procedures a comparison is made separately with rates including SSI identified on readmission to hospital within 30 days of the operation. In order to limit the influence of case mix on these comparisons only patients with a NNIS score of 0 have been included in these funnel plots. The funnel plots in this report show the upper and lower 95% confidence limits as curved lines. If an individual NHS board s rate was outwith the 95% confidence limit, this would be regarded as an outlier, suggesting that that NHS board had a SSI rate which was significantly different to other NHS boards. Rates of compliance with relevant recommendations from published SIGN guidelines are shown by procedure category. As all CABG and cardiac procedures reported to the SSI programme were undertaken within one NHS board, analysis of these procedure categories will be limited to number of procedures performed, inpatient SSI, inpatient SSI rates and patient demographics and will not be included in more detailed analyses. Cranial surgery SSI surveillance has not been selected by any NHS board to be performed during 2008 and 2009 and therefore has not been included in the results. All confidence limits in this report are produced using the Wilson s approximation to the binomial distribution

12 4 Results 4.1 Procedures The number of procedures included in the surveillance programme has increased each year, with data on procedures perform in the seventh year. The annual number of operations by procedure category are shown in Table 1. Table 1: Annual number of operations by procedure category Procedure Total Abdominal hysterectomy Breast surgery CABG Caesarean section Cardiac surgery Hip arthroplasty Knee arthroplasty Major vascular surgery Open reduction of long bone fracture Total The total number of procedures included in the surveillance programme has increased year on year since 2003, resulting in three times as many procedures included in surveillance in 2009 than there were in Patient demographics The median age and proportion of female patients for each procedure category during 2003 to 2009 and 2009 are described in Table 2. Table 2: Median age and proportion of female patients by procedure category 2003 to 2009 and to Procedure Median age % female patients Median age % female patients Abdominal hysterectomy % % Breast surgery % % CABG % % Caesarean section % % Cardiac surgery % % Hip arthroplasty % % Knee arthroplasty % % Major vascular surgery % % Open reduction of long bone fracture % % The median age and percentage of female patients did not significantly change between the two time periods for each of the nine procedure categories. 12

13 For patients undergoing caesarean section, who had their age recorded, the majority were under 35 years old (73.0%) with a further 26.7% aged between 35 and 44 years old. There was only 44 patents (0.3%) who were 45 years or over. For hip arthroplasty, for those patients who had their age recorded, the majority of patients were 65 years or older (70.6%). 4.3 Incidence of SSI in 2009 A total of procedures were reported during Table 3 shows the inpatient SSI (cumulative incidence) rates by procedure over this period. Table 3: Number of participating boards, procedures, inpatient SSI and inpatient cumulative SSI incidence rate by procedure, 2009 Procedure Number of NHS boards Number of procedures Inpatient SSI Inpatient SSI Rate (%) (95% CI) Abdominal hysterectomy (1.1, 3.0) Breast surgery (0.2, 1.3) CABG (3.4, 6.3) Caesarean section (0.3, 0.6) Cardiac surgery (0.6, 3.4) Hip arthroplasty (0.6, 1.0) Knee arthroplasty (0.2, 0.5) Major vascular surgery (1.7, 6.3) Open reduction of long bone fracture (0.3, 1.1) Total (0.6, 0.8) The inpatient cumulative incidence SSI rates ranged from CABG with a rate of 4.7% to knee arthroplasty with a rate of 0.3%. To allow for differences in post operative length of stay it is possible to calculate a rate of SSI that uses the number of post operative days of follow-up as the denominator rather than the number of procedures. This rate is called the incidence density and is expressed as the number of SSI per 1000 post operative days of follow-up (Table 4). This method is particularly useful when comparing SSI rates over a sustained period of time when practice can change or in comparing between different healthcare systems, e.g. between countries. Table 4: Number of patient days, inpatient SSI and inpatient SSI incidence density SSI per 1000 post operative inpatient days, by category of procedure, 2009 Procedure Patient days Inpatient SSI Inpatient SSI Rate (%) (95% CI) Abdominal hysterectomy (2.4, 6.4) Breast surgery (1.8, 5.0) CABG (4.2, 7.8) Caesarean section (1.0, 1.7) Cardiac surgery (0.8, 4.2) Hip arthroplasty (0.9, 1.3) Knee arthroplasty (0.3, 0.9) Major vascular surgery (1.4, 5.6) Open reduction of long bone fracture (0.3, 1.1) Total (1.1, 1.5) 13

14 The highest incidence density SSI rate was reported in CABG procedures at 5.8 SSI per 1000 patient days and the lowest rate was reported in knee arthroplasty at 0.5 SSI per 1000 patient days. 4.4 Incidence of SSI from 2003 to 2009 A total of procedures were reported during the surveillance period 2003 to Table 5 shows the inpatient SSI (cumulative incidence) rates by procedure over this period. Table 5: Number of procedures, inpatient SSI and inpatient cumulative incidence SSI rate by procedure, 2003 to 2009 Procedure Number of NHS boards Number of procedures 2003 to 2009 Inpatient SSI Inpatient SSI Rate (%) (95% CI) Abdominal hysterectomy (1.4, 2.0) Breast surgery (0.6, 1.2) CABG (3.5, 4.9) Caesarean section (0.9,1.0) Cardiac surgery (1.2, 3.3) Hip arthroplasty (1.0, 1.2) Knee arthroplasty (0.4, 0.6) Major vascular surgery (5.9, 8.7) Open reduction of long bone fracture (1.1, 1.6) Total (1.0, 1.1) The highest inpatient SSI rate over this period was in major vascular surgery at 7.2% and the lowest inpatient SSI rate was found in knee arthroplasty at 0.5%. The incidence density SSI rates for the whole period of surveillance (2003 to 2009) are shown in Table 6. Table 6: Incidence density of inpatient SSI per 1000 post operative inpatient days with 95% confidence interval, by category of procedure, 2003 to to 2009 Procedure Patient days Inpatient SSI Inpatient SSI Rate (%) (95% CI) Abdominal hysterectomy (2.8, 4.1) Breast surgery (1.9, 3.8) CABG (4.1, 5.7) Caesarean section (2.4, 2.8) Cardiac surgery (1.4, 3.9) Hip arthroplasty (1.3, 1.5) Knee arthroplasty (0.6, 0.8) Major vascular surgery (4.8, 7.2) Open reduction of long bone fracture (1.0, 1.5) Total (1.7, 1.9) 14

15 The highest SSI rate was in major vascular surgery at 5.8 SSI per 1000 patient days and the lowest rate was in knee arthroplasty with 0.7 SSI per 1000 patient days. 4.5 Incidence of SSI by age There was no significant difference between the age of patients that developed an SSI following caesarean section surgery than those who did not (t = 0.307, p = 0.714). Patients that developed an SSI following hip arthroplasty surgery were significantly older (t = , p = 0.001) than those patients who did not develop an infection. Caesarean section procedures are routinely performed in a younger patient population and this is confirmed by these results. 15

16 4.6 Characteristics of SSI The distribution of the type of SSI detected during the inpatient stay for the periods 2003 to 2009 and 2009 are presented in Figure 1 and Figure 2 respectively. 100% Figure 1: Infection type by procedure, inpatient SSI 2003 to % 80% Percentage 70% 60% 50% 40% Not recorded Organ/Space Deep Superficial 30% 20% 10% 0% Abdominal hysterectomy Breast surgery Caesarean section Hip arthroplasty Knee arthroplasty Major vascular surgery Procedure Reduction of long bone fracture Figure 2: Infection type by procedure, inpatient SSI % 90% Percentage 80% 70% 60% 50% 40% Not recorded Organ/Space Deep Superficial 30% 20% 10% 0% Abdominal hysterectomy Breast surgery Caesarean section Hip arthroplasty Knee arthroplasty Major vascular surgery Reduction of long bone fracture Procedure Changes in the proportions of SSI for the abdominal hysterectomy, breast surgery and major vascular procedures should be treated with caution due to the small number of inpatient SSI detected for these procedures. The most notable difference in the distribution of SSI between the full time period and the latest year is the increased proportion of deep SSI identified for the hip arthroplasty, knee arthroplasty and open reduction of long bone fracture procedures from 25.5%, 23.8% and 12.2% respectively during 2003 to 2009 to 46.1%, 46.6% and 44.4% in However this analysis does not take into account the increasing number of procedures within each category over the time period , therefore analysis of SSI rates for deep infections were performed (Figure 3). 16

17 Figure 3: SSI rate for deep infection by procedure, inpatient SSI % 0.9% 0.8% Hip arthroplasty Knee arthroplasty Open reduction of long bone fracture 0.7% SSI rate 0.6% 0.5% 0.4% 0.3% 0.2% 0.1% 0.0% For knee arthroplasty the SSI rate for deep infections was highest in 2003 at just over 0.3% before decreasing year on year until In 2009 the SSI rate for deep infections in knee arthroplasty was just over 0.1%. For open reduction of long bone fracture the SSI rate for deep infection was highest in 2006 at just under 0.3%. Hip arthroplasty procedures from 2005 shows an increase SSI rates for deep infection to almost 0.4% in Inpatient incidence density of SSI, by year of surveillance, 2003 to 2009 Figures 4 to 10 describe the inpatient SSI incidence density rate from 2003 to 2009 for each procedure. The CABG and cardiac surgery within this report represent cases treated within one NHS board and are therefore not included in this section. Figure 4 shows the annual inpatient SSI incidence density rate with 95% confidence intervals for abdominal hysterectomy procedures. Figure 4: Annual rate of inpatient SSI per 1000 patient days (incidence density) with 95% CI for abdominal hysterectomy, 2003 to IP Incidence Density SSI rate (SSI/1000 patient days) Year 17

18 The confidence intervals around these rates are wide due to the relatively small number of procedures reported in each year and therefore should be treated with caution. There was no significant annual linear trend in the inpatient SSI rate ( c2 = 7.605, df = 6, p = 0.268). The annual inpatient SSI incidence density rates for breast surgery from 2003 to 2009 are shown in Figure 5. Figure 5: Annual rate of inpatient SSI per 1000 patient days (incidence density) with 95% CI for breast surgery, 2003 to IP Incidence Density SSI rate (SSI/1000 patient days) Year There was a significant downward linear trend in the annual SSI rate ( c2 = , df = 6, p = 0.024). Since 2006 there has been a non-significant increase noted in the annual SSI rate. 18

19 The annual inpatient SSI incidence density rates for caesarean section procedures are shown in Figure 6. Figure 6: Annual rate of inpatient SSI per 1000 patient days (incidence density) with 95% CI for caesarean section, 2003 to IP Incidence Density SSI rate (SSI/1000 patient days) Year The number of operations reported for this procedure increased from 2007, when reporting became mandatory and this is reflected in the narrower confidence intervals since There was a significant decrease noted in the annual SSI rates from 2003 to 2009 ( c2 = , df = 6, p < ). When procedures carried out from the introduction of mandatory surveillance in caesarean sections are considered, i.e to 2009, a significant reduction in the annual SSI rate over this period is found ( c2 = , df = 2, p < ). The annual inpatient SSI incidence density rates for hip arthroplasty from 2003 to 2009 are shown in Figure 7. Figure 7: Annual rate of inpatient SSI per 1000 patient days (incidence density) with 95% CI for hip arthroplasty, 2003 to IP Incidence Density SSI rate (SSI/1000 patient days) Year 19

20 There was a significant reduction in this rate over the period 2003 to 2009 ( c2 = , df = 6, p < ), when procedures from the introduction of mandatory surveillance are considered i.e to 2009, there is no significant linear reduction in the SSI rate ( c2 = 0.476, df = 2, p = 0.788). Figure 8 presents the annual inpatient SSI incidence density rates from 2003 to 2009 for knee arthroplasty procedures. Figure 8: Trends in rate of inpatient SSI per 1000 patient days (incidence density) with 95% confidence intervals for knee arthroplasty 2.0 IP Incidence Density SSI rate (SSI/1000 patient days) Year This rate decreased significantly over the period 2003 to 2009 ( c2 = , df = 6, p < ). There was a non-significant increase in the SSI rate from 2008 to The annual inpatient SSI incidence density rates from 2003 to 2009 for major vascular surgery are presented in Figure 9. 20

21 Figure 9: Trends in rate of inpatient SSI per 1000 patient days (incidence density) with 95% confidence intervals for major vascular surgery IP Incidence Density SSI rate (SSI/1000 patient days) Year There was a significant reduction in the SSI rate during this period for this procedure ( c2 = , df = 6, p = 0.003). A large decrease in the inpatient SSI incidence was observed between 2006 and The annual inpatient SSI incidence density rates from 2003 to 2009 for open reduction of long bone fracture surgery are presented in Figure 10. Figure 10: Trends in rate of inpatient SSI per 1000 patient days (incidence density) with 95% confidence intervals for open reduction of long bone fracture IP Incidence Density SSI rate (SSI/1000 patient days) Year The SSI rate fell significantly from 2003 to 2009 ( c2 = , df = 6, p < ), the largest individual decrease in inpatient SSI incidence was observed between 2006 and

22 4.8 Incidence of SSI by risk group Table 7 describes the number of procedures and inpatient cumulative incidence SSI rates by NNIS risk index for the periods 2003 to 2009 and for During the period 2003 to 2009 the cumulative incidence SSI rate increased with an increasing NNIS score for all procedures except major vascular surgery, although this difference was not statistically significant. During 2009 the cumulative incidence SSI rate did not increase with increasing NNIS score and this may be due to the smaller number of procedures included. Table 7: Cumulative incidence of inpatient SSI, by category of surgical procedure, by NNIS risk index for, 2003 to 2009 and 2009 Procedures Risk Index 0 Risk Index 1 Risk Index 2 Risk Index 3 Not Recorded Number of SSI Number of SSI Number of SSI Number of SSI Number of SSI procedures procedures procedures procedures procedures Abdominal hysterectomy % % % 2 0.0% % Breast surgery % % % % Caesarean section % % % % % Hip arthroplasty % % % % % Knee arthroplasty % % % % % Major vascular surgery % % % 1 0.0% % Open reduction of long bone % % % % % fracture 2009 Procedures Number of procedures SSI Number of procedures SSI Number of procedures SSI Number of procedures SSI Number of procedures Abdominal hysterectomy % % % 2 0.0% % Breast surgery % % 7 0.0% % Caesarean section % % % 1 0.0% % Hip arthroplasty % % % % % Knee arthroplasty % % % % % Major vascular surgery % % % 1 0.0% % Open reduction of long bone fracture % % % % SSI There were a proportion of procedures that were not recorded for NNIS risk index. HPS are working closely with NHS boards to improve recording methods to reduce the number of NNIS risk index not recorded. 22

23 4.9 Readmission Surveillance for hip arthroplasty Tables 8 and 9 show the number of procedures, number of inpatient and readmission SSI including infections detected up to 30 days after surgery, the proportion of SSI detected at readmission and inpatient and readmission SSI cumulative incidence rate by operation sub category for hip arthroplasty procedures in 2007 to 2008 and for This includes the period since the introduction of mandatory readmission surveillance for this procedures in January Table 8: Number of procedures, SSI and rate of SSI by hip arthoplasty subcategory 2007 to 2009 Procedure Number of procedures Inpatient SSI Inpatient and readmission SSI % detected on readmission IP SSI rate IP & Readmission SSI rate Primary hemi arthroplasty % 1.4% 1.9% Primary total hip % 0.4% 0.8% replacement Revision of hemi % 4.0% 4.0% arthroplasty Revision of total hip % 1.3% 1.8% replacement Total* % 0.8% 1.2% * There were 341 procedures resulting in three inpatient SSI that did not have their sub category recorded. Table 9: Number of procedures, SSI and rate of SSI by hip arthoplasty subcategory for 2009 Procedure Number of procedures Inpatient SSI Inpatient and readmission SSI % detected on readmission IP SSI rate IP & Readmission SSI rate Primary hemi arthroplasty % 1.6% 2.2% Primary total hip % 0.3% 0.7% replacement Revision of hemi % 5.3% 5.3% arthroplasty Revision of total hip % 1.3% 1.8% replacement Total* % 0.8% 1.2% * There were 207 procedures resulting in three inpatient SSI that did not have their sub category recorded. 23

24 The proportion of SSI detected on readmission showed a small increase from 33.6% in 2007 to 2009 to 34.8% in The method of detection for SSI identified in hip arthroplasty procedures from 2007 to 2009 is described in Figure % Figure 11: Method of detection by year for hip arthroplasty to day 30, 2007 to % % Detection method 80% 70% 60% 50% 40% Not recorded Readmission to day 30 Inpatient 30% 20% 10% 0% Year The proportion of SSI identified during the inpatient admission period varied with 71.7% in 2007, 60.2% in 2008 and 63.3% in The proportion of SSI detected on readmission varied with 27.3% in 2007, 39.0% in 2008 and 33.3% in The proportion of SSI that were not recorded for their detection method was highest in 2009 (3.3%). HPS are working closely with NHS boards to improve recording methods, to reduce the number of not recorded. Figure 12 presents the type of SSI detected by inpatient and readmission surveillance for hip arthroplasty procedures in

25 Figure 12: Type of SSI detected in hip arthroplasty by inpatient and readmission surveillance to day 30, % 90% 80% 70% Not recorded Organ/Space Deep Superficial Percentage 60% 50% 40% 30% 20% 10% 0% Inpatient Detection method Readmission As would be expected there was a higher proportion of deep or organ/space infections for infections detected on readmission to hospital than in infections detected as an inpatient ( c2 = 4.39, df = 1, p = 0.036) PDS Surveillance for caesarean section This section covers the period since the introduction of mandatory PDS surveillance for these procedures in January PDS until day 10 was made mandatory in April 2009 and this is accounted for in the analysis. Figure 13 describes the proportion of SSI detected the 10th post operative day at each stage of the patient journey for 2007 to 2008 and for % Figure 13: Proportion of SSI by method of detection for caesarean sections, 2007 to 2009 % Detection method 90.0% 80.0% 70.0% 60.0% 50.0% 40.0% 30.0% Not recorded Post discharge On readmission During the admission period 20.0% 10.0% 0.0% Year 25

26 The proportion of SSI detected by PDS to day 10 post operatively (not including those patients whose method of detection was not recorded (n=14)) varied from 80.4% in 2007, 84.9% in 2008 and 85.3% in Post discharge surveillance to day 10 post operatively for caesarean section was standardised in April From April to December 2009, the proportion of caesarean section SSI detected by PDS to day 10, (not including those patients whose method of detection was not recorded), was 83.5% (253 of 303 SSI), with the vast majority having a superficial infection (96.0%).There was a further 4.0% with deep infections and there were no organ/ space infections reported to HPS from April to December Variation in SSI Rate by NHS board Figures 14 to 18 indicate the variation in SSI rates by NHS board for the selected categories of surgery for 2009 only. The inter-board comparisons presented below were carried out using data for procedures where the NNIS risk score was equal to zero. Some procedure categories have not been included in these analyses as they do not meet the criteria for this part of the analysis which requires more than four NHS boards participating in the surveillance programme and only NHS boards that performed more than 30 procedures within the selected category of surgery to be included. As previously noted, HPS operate a quarterly exception reporting system and those boards that have been highlighted have been contacted by HPS. Key to NHS boards: AA Ayrshire & Arran BR Borders DG Dumfries & Galloway FF Fife FV Forth Valley GR Grampian GGC Greater Glasgow & Clyde HG Highland LO Lothian LN Lanarkshire NW National Waiting Times Centre TY Tayside Figure 14 shows a funnel plot of the SSI rate for inpatient caesarean section by NHS board in Figure 14: Cumulative incidence (no of SSI per 100 procedures) of inpatient SSI (NNIS = 0) by NHS board in 2009 for caesarean section procedures (n = 11381) 1.4% 1.2% 1.0% SSI Rate 0.8% 0.6% FF GR LO 0.4% FV TY 0.2% LN GGC BR DGHG AA 0.0% Number of procedures 26

27 One NHS board (NHS Lothian) collecting caesarean section data in 2009 reported an inpatient SSI incidence rate that was slightly higher in relation to the other NHS boards collecting data. Figure 15 shows a funnel plot of the SSI rate for caesarean section proceedures including infections detected by PDS up to the 10th post operative day from April to December Figure 15: Cumulative incidence (no of SSI per 100 procedures) of SSI rate including inpatient and PDS to day 10 (NNIS = 0) by NHS board from April to December 2009 for caesarean section procedures (n = 8814) 12.0% 10.0% 8.0% SSI Rate 6.0% HG FF 4.0% 2.0% 0.0% DG BR TY AA FV LN GR LO Number of procedures Two NHS boards (NHS Highland and NHS Fife) collecting caesarean section data, between April and December 2009, reported an SSI incidence rate including PDS to day 10 that were slightly higher in relation to the other NHS boards collecting data and these boards were alerted to this by HPS. GGC Figure 16 shows a funnel plot of the inpatient SSI rate for hip arthroplasty by NHS board in

28 Figure 16: Cumulative incidence (no of SSI per 100 procedures) of inpatient SSI (NNIS = 0) by NHS board in 2009 for hip arthroplasty (n = 4294) 5.0% 4.5% 4.0% 3.5% SSI Rate 3.0% 2.5% DG 2.0% 1.5% 1.0% 0.5% 0.0% FVBR AA FF LN HG TY GR NW Number of procedures None of the NHS boards collecting hip arthroplasty data in 2009 reported an inpatient SSI incidence rate that was significantly higher in relation to the other NHS boards collecting data. LO GGC Figure 17 shows a funnel plot of the SSI rate for hip arthroplasty including infections detected on readmission to the 30th post operative day. Figure 17: Cumulative incidence (no of SSI per 100 procedures) of inpatient and readmissions to day 30 SSI (NNIS = 0) by NHS board in 2009 for hip arthroplasty (n = 4294) 5.0% 4.5% 4.0% 3.5% 3.0% SSI Rate 2.5% 2.0% DG 1.5% 1.0% FV BR LN HG TY AA 0.5% LO GGC NW FF GR 0.0% Number of procedures None of the NHS boards collecting hip arthroplasty data in 2009 reported an SSI incidence rate including readmissions to day 30 that was significantly higher in relation to the other NHS boards collecting data. 28

29 Figure 18 shows a funnel plot of the inpatient SSI rate for knee arthroplasty by NHS board in Figure 18: Cumulative incidence (no of SSI per 100 procedures) of inpatient SSI (NNIS = 0) by NHS board in 2009 for knee arthroplasty (n = 2839) 3.0% 2.5% 2.0% SSI Rate 1.5% 1.0% GR 0.5% TY 0.0% FV HG FF Number of procedures None of the NHS boards collecting knee arthroplasty data in 2009 reported an inpatient SSI incidence rate that was significantly higher in relation to the other NHS boards collecting data. NW GGC 4.12 Compliance with guidelines SIGN Guideline 104, Antibiotic Prophylaxis in Surgery 20 is aimed at reducing inappropriate prophylactic prescribing and recommends intravenous prophylactic antibiotics should be given less than or equal to 30 minutes before the skin is incised. Figure 19 shows the timing of antibiotic prophylaxis for hip and knee arthroplasty procedures carried out in Figure 19: Timing of administration of antibiotic prophylaxis for hip and knee arthroplasty surgery in 2009 (n = 15404) Number of procedures >30 mins pre-op <30 <30 mins pre-op Peri-op <=3 hours post-op >3 hours post-op Antibiotic timimng 29

30 During this period 69.0% of hip and knee arthroplasty patients received their antibiotic prophylaxis within the recommended period of < 30 minutes before the skin is incised. Data was missing for 608 orthopaedic procedures. HPS are working closely with NHS boards to improve recording methods, to reduce the number of not recorded. SIGN guideline 104 Antibiotic prophylaxis in surgery 20 recommends that prophylactic antibiotics should not be administered for more than 24 hours (Figure 20). Figure 20: Duration of Prophylactic antibiotics therapy in caesarean sections and orthopaedic surgery in 2009 (n = 30511) 100% 90% 80% 70% Not recorded <=24 hours > 24 hours Percentage 60% 50% 40% 30% 20% 10% 0% Caesarean section Hip arthroplasty Knee arthroplasty Open reduction of long bone fracture Procedure The proportion of patients having antibiotic prophylaxis for more than 24 hours was 2.4% for caesarean sections, 5.4% in hip arthroplasty procedures, 3.9% in knee arthroplasty and 1.7% for open reduction of long bone procedures. SIGN guideline 104 Antibiotic prophylaxis in surgery 20 recommends that antibiotic prophylaxis should be administered in compliance with local guidelines. Figure 21 describes the compliance with the guideline recommendation. 30

31 Figure 21: Prophylactic antibiotics given in accordance with local guidelines for caesarean section and orthopaedic surgery in 2009 (n = 30511) 100% 90% 80% 70% Not recorded No Yes Percentage 60% 50% 40% 30% 20% 10% 0% Caesarean section Hip arthroplasty Knee arthroplasty Open reduction of long bone fracture Procedure The proportion of procedures where antibiotic prophylaxis was not given in compliance with local guidelines was 3.8% for hip arthroplasty procedures, 3.4% for knee arthroplasty procedures, 3.3% for open reduction of long bone fracture procedures and 2.4% for caesarean sections. This information was not recorded in 29.8% of procedures. HPS have recently developed quarterly reporting for antimicrobial teams to monitor local antibiotic prophylaxis for mandatory procedures. SIGN guideline 104 also recommends antibiotic impregnated cement for cemented joint replacements. Figure 22 shows the level of compliance with this guideline recommendation. Figure 22: Antibiotic impregnated cement used for hip and knee arthroplasty in 2009 (n = 12173) Yes 88.3 No Not recorded During 2009 antibiotic impregnated cement was used in 88.3% of hip and knee arthroplasty procedures which required cement. Antibiotic impregnated cement was not used in 5.6% of procedures which required cement and this was not recorded for 6.1% of hip and knee arthroplasty procedures which required cement. 31

32 Figure 23 shows compliance with the Specialist Advisory Committee of the Joint Committee on Higher Surgical Training best practice guideline that a Consultant should either operate or be present in theatre during hip and knee arthroplasty procedures in Figure 23 : Consultant performing procedure or present within theatre for hip and knee arthroplasty surgery in 2009 (n = 16012) 6.5% 4.0% 14.0% 75.5% Consultant operating Consultant present No Consultant present Not recorded Compliance with this is 89.5% in all procedures and 93.2% in procedures where this information is recorded. SIGN guideline recommends that all patients undergoing hip and knee arthroplasty surgery should have venous thromboembolism prophylaxis (either chemical or mechanical); Figure 24 describes compliance with this recommendation in hip and knee arthroplasty procedures in Figure 24: Administration of venous thromboembolism prophylaxis for orthopaedic surgery in 2009 (n = 16012) 1.2% 0.8% 12.6% 30.3% 55.1% Both Chemical Mechanical N o Not recorded Prophylaxis for thromboembolism was administered to 86.2% of orthopaedic patients, this was not recorded for 12.6% of these procedures. 32