Assuring Data Quality Dept. of Healthcare-Associated Infection & Antimicrobial Resistance, Health Protection Agency Jennie Wilson Programme Leader – SSI Surveillance

2005 Hip prosthesis: inter-country rate (incidence density) 2005 Hip prosthesis: inter-country rate (cumulative incidence)

External benchmarks External benchmarks are a powerful driver for effecting change, but require standardised data collection methods standardised analysis high data quality central co-ordination Gaynes 1997

Why is data quality so important locally? Do you know whether action is required? real problems? poorly collected data?

SSI Surveillance Basic methodology Targeted at categories of clinically similar operative procedures Data collection form completed for each relevant operation (denominator) Systematic (active) surveillance after each operation to detect infections (numerator)

Methods of identifying patients with SSI (numerator) Active Designated, trained personnel, use a variety of data sources to determine whether an HAI has occurred Sensitivity = % Passive HAI identified and reported by people other than designated, trained personnel. Requires fewer people but unreliable, definition not applied consistently Sensitivity: 14-34% (Perl, 1998)

Surveillance methods: Sensitivity of case finding Lab-based phone Sensitivity 36% 1.2hrs / 100 beds / week Temperature / treatment chart Sensitivity 65% 6.5 hours / 100 beds / week Lab-based, ward liaison Sensitivity 76% 6.4 hours / 100 beds / week Glenister et al 1992

Systematic surveillance for SSI Lab-based ward liaison 1.Visit ward/patient 3 times per week – discuss patients with ward staff – check medical / nursing records – check temperature / treatment charts 2.Review microbiology reports daily – identify positive surgical site reports

Definitions of surgical site infection (CDC) Superficial incisional involves only skin or subcutaneous tissue occurs within 30 days of surgery Deep incisional involves fascial or muscle layers occurs within 30 days, implants within 1 year Organ/space part of anatomy opened / manipulated infection appears related to surgery occurs within 30 days, implants within 1 year

Superficial Incisional Infection Must meet one of the following criteria: 1. Purulent drainage from superficial incision 2. Culture of organisms from fluid/tissue 3. At least 1 symptom of inflammation ( pain, tenderness, localised swelling, redness, heat) and incision deliberately opened to manage infection 4. Clinicians diagnosis of superficial SSI

Deep Incisional Infection Must meet one of the following criteria: 1.Purulent drainage from deep incision 2. Deep incision dehisces / deliberately opened and patient has 1 symptom : fever, localised pain/tenderness 3. Abscess / other evidence of infection in deep incision: re-operation / histopathology / radiology 4. Clinicians diagnosis of deep infection

Identifying SSI Review patients systematically whilst they are in hospital Do not rely on reviewing case-notes after discharge to find SSIs If a patient is prescribed antibiotics do not assume these are for SSI – check with clinician Check significance of positive microbiology cultures Make sure any SSI identified post-discharge also meets the definition

Is this an SSI…….? Nursing record states: ‘Wound oozing ++ from small lower section. Pressure dressing applied’ Oozing what: Clear (serous) fluid, blood, pus? What was the condition of the suture line? Red, swollen, dehisced Was a wound swab taken, if so why?

Criteria for SSI checklist Weblink data entry (SSISS)

Validation studies Mannien et al 2007: PREZIES, Netherlands Reviewed 859 medical charts; 149 SSI Validation team = ‘gold standard’ PPV = 0.97; NPV = 0.99 McCoubrey et al 2005: SSI surveillance, Scotland 91 SSI reported validated by case note review 10/27 hospitals criteria not recorded PPV 94.6% (95%CL 87.9 – 98.2); NPV 99.4 (95% CL 98.3 – 99.9) (assuming not recorded data valid)

NNIS SSI ‘Risk Index’ Each operation is scored, and results stratified, using 3 major risk factors associated with SSI*: ASA pre-operative assessment score Wound class Duration of surgery (T time) Score between 0 and 3 *Culver et al (1991)

Risk Index factors ASA classification of physical illness 1: normal healthy patient 2: mild systemic disease 3: severe systemic disease 4: incapacitating systemic disease 5: moribund, little chance of survival Wound classification Clean: no signs of infection, no body ‘tracts’ Clean-contaminated: body tract entered Contaminated: spillage form GIT, inflammation, open trauma Dirty: pus, perforated viscera, delayed open trauma, faecal contamination Changed by pre-op and intra-op events

T time association between p value and cut point for duration of operation (abdominal hysterectomy) Leong et al 2006

Trend in rate of SSI by Risk index group

Effect of indirect standardisation on crude rates of SSI (vascular surgery)

Percentiles 90th 75th 50th 25th 10th Distribution of the incidence of surgical site infection by category of surgical procedures Source: SSI Surveillance Service, CDSC October 1997 to December 2003

Crude rates of SWI for vascular surgery (95% CL) by hospital 90 th percentile 50 th percentile Data to December 2001

Funnel plots used to account for variation in sample size Total hip prosthesis, January 2000 – March 2005 Cumulative incidence

Incidence density

Funnel plots to adjust for variation in sample size and length of post-op stay Incidence density/ 1000 post-op in-patient days

Length of stay in elective surgery is reducing

Proportion of SSI detected pre & post discharge Barrett et al 2000

Post-discharge surveillance study Post-discharge surveillance method Resources data collection, informing/contacting patients General practitioners/district nurses – poor response rate to questionnaire Patients – better response; +/- reliability Sensitivity of case-finding active vs. passive surveillance reliability Barrett et al 2000

Response rate to PDS patient questionnaires n = 6159 Barrett et al 2000 Response rate affected by ethnic group and age