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Surveillance Methodology and Economic Burden of SSIs

Surveillance Methodology and Economic Burden of SSIs. Maureen Spencer, RN, M.Ed , CIC Infection Preventionist Consultant Boston, MA - USA. Purpose of the Infection Control and Prevention Program. Surveillance – detect cases Control - outbreaks, clusters or increasing trends in data

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Surveillance Methodology and Economic Burden of SSIs

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  1. Surveillance Methodology andEconomic Burden of SSIs Maureen Spencer, RN, M.Ed, CIC Infection Preventionist Consultant Boston, MA - USA

  2. Purpose of the Infection Control and Prevention Program • Surveillance – detect cases • Control - outbreaks, clusters or increasing trends in data • Implement prevention measures

  3. Surveillance System and CDC Definitions

  4. Developed Algorithms For Surveillance (Each Category)

  5. Case definition • Case definitions are designed to capture all potential cases of a disease/condition without contaminating the dataset with extraneous materials • NHSN is, by definition, our basic service • Special case definitions may be required for specific issues or for outbreaks

  6. Case definitions • Outbreak • May want to date or unit define • May want to include symptoms or manifestations • Case control studies • Permit selection of control group (those without the condition under study) • Associated with the event or process

  7. Data analysis • Data are systematically compiled and interpreted • Data are analyzed using statistical methods • Date are compared over time to internal and external databases • Comparative databases are used when undesirable variation is identified

  8. Numbers • Numerator – the “top” number which is also the number of cases identified • Denominator – the “bottom number” –(down below) is the total number of individuals studied • Rate – the result of dividing the numerator by the denominator and multiplying by a factor

  9. The “Factor” • There is no established “factor” for most statistical math in epidemiology • Generally report surgical and other similar infection as x/100 events • Generally report device related infections by device day x/1000 device days

  10. Measures of occurrence • Incidence • Measure of frequency with which an event occurs in a population over a specified period of time • New cases • Prevalence • Proportion of persons in a population with a particular disease at a specific point in time (point prevalence) or over a specified time period (period prevalence) • Existing cases

  11. Studies • Case Control – two groups, identical, but one with the characteristic under study, and other without. General 1:3 (power) • Cohort – all people in a group (enter together, and then observe for occurrence of disease/condition) • Prospective – looking forward • Retrospective – looking backward

  12. Bias • Bias can be defined as “any systematic error in the design, conduct or analysis of a study that results in a mistaken estimate of an exposure’s effect on the risk of disease” • Selection Bias • Information Bias

  13. The monthly record of cases • Record demographic data for each case • Use consistent methods • Column A: Last Name • Column B: First Name • Column C: Medical Record #Physician • Physician name • Physician identification # (check, as often there are two different numbers in the hospital) • Age – useful in stratification • Gender – equivocal data set • Admission date (critical!) • Onset date (used to calculate # hospital days admission to onset)

  14. Line Listing • Line List: A line list is an organized, detailed list of each record of a surgical site infection Example • Suppose you are interested in looking at all CLABSIs in 2010 that occurred in the ICU and the Orthopedic Unit • You would like to produce a line list that includes basic patient demographics (patient ID, DOB, gender, and age at event), information on the event (date admitted, date of surgey, date of onset, location of patient when SSI developed

  15. Line list heading – Depends on the HAI • Infection site • Use standard nomenclature - NHSN • SSI • SST • CAUTI • Procedure codes • Procedure date • Surgeon code • Surgeon assistant and others in the room • Date of Admission • Date of Onset of Infection • Antibiotics • ASA score • Incision time • Closure time • Patient room number

  16. Next columns • Organism • Use standard nomenclature! • CNS vs. Coag neg staph vs. S. epidermidis • Spell the words correctly • Culture site • Final attribution – Hosp Onset, Comm Onset, Comm Acquired • Comment field– generally cannot sort by anything except the first word but useful for keeping notes

  17. Frequency Table • Frequency Table: A frequency table is an organized display of counts and percentages • The data are organized by a row variable and a column variable, and the frequency table provides a count of the number of observations in the data set that meet the specifications of both the row and column variables Example • Suppose you are interested in looking at the distribution of each SSI across the different services in your facility, for all events that were identified in 2012

  18. EXAMPLE OF HAI FREQUENCY TABLE IN EXCEL FILE UHS HAI Dashboard

  19. Descriptive Epidemiology • Cross tabulations: • infections/organisms • infections/nursing units • infections/services • infections/risk factors • Evaluate trends and clusters • Conduct studies and investigations • Retrospective case reviews, Case-Control Studies

  20. Examples of Cross Tabulations • CLABSI by ICUs • CLABSI by device type • CLABSI by organisms • SSIs by services • SSIs by surgeons • SSIs by nursing unit • Risk factors by SSIs • SSI rates over a time period

  21. SSI by Service - 2012

  22. Example CLABSI Analysis 2011-2012 What do these numerators mean? Next calculate rates by line days

  23. CLABSI BY ORGANISMS - 2012

  24. SSI RATES

  25. SSIs BY SURGEONS - RATES

  26. Risk Factors for Infections ? What percentage of non-infected patients had risk factors ? What percentage of Surgeon I patients had these risk factors Obesity diabetes risk factors at this institution Staples are used often which may be increasing the risk Drains being used in orthopedic surgery – increase risk

  27. Pie Chart • Pie Chart: A pie chart is a graphical representation of data. The different slices of the pie represent different values of a variable, with the relative size of the slice representing the amount of data included in the slice

  28. Pie Chart Example • The top value for each slice is the value of the “chart variable” (e.g., location). • The second value is a count of the number of events included in each slice of the pie Example: • Distribution of HAIs

  29. Bar Chart • Bar Chart: A bar chart is a graphical representation of data where the length or height of the bars represents counts of cases or rates

  30. Number of Cases by Surgery Date

  31. Days from Surgery to Infection- HPRO & KPRO

  32. Orthopedic Surgical Site Infection Rates OR Environmental controls: Traffic, Attire,Scrub, Air Handling Antibacterial sutures MRSA and Staph aureus Elimination Program CHG/Alcohol Prep Laminectomy outbreak due to locally administered steroids (depomedrol) 7 x increase risk of infection if obese and diabetic Increase in hematomas after use of Lovenox and Plavix

  33. NEBH SSI Rates 2003 – 2010(outpatient and inpatient infections) 2009 - Total hip investigation – increase in post-op hematomas in infected patients being evaluated by a case-control study 2008 – Total knee investigation – noticed increase rate in patients receiving toradol, marcaine and duromorph – needle on syringe was not being changed between each vial – changed practice 2007 – Laminectomy rate increased – case control study revealed locally adminiistered steroids increased infection rate in obese/diabetic pts 40

  34. Run Chart • Run Chart: A run chart (or control chart) is a line graph showing change in a variable over a selected time period • This is a useful output if you would like to view, for example, the change in rates over time and 2 standard deviation above the mean

  35. MRSA/MSSA Eradication Program Instituted AMD Gauze and Standardized dressing technique

  36. Standardized Infection Ratio (SIR) • Standardized Infection Ratio (SIR), a statistic used to measure relative difference in HAI occurrence during a reporting period compared to a common referent period (i.e., standard population). • SIR compares the actual number of HAIs with the predicted number based on the baseline U.S. experience (i.e., standard population), adjusting for several risk factors that have been found to be most associated with differences in infection rates

  37. Next Step: Calculate SIR by HAI by facility and compare to national data from NHSN

  38. The “p” value • The p value is the probability that an event will occur in a given set of trials • A p of 1 means it will occur every time the trial occurs (if there were 100 “z” in a pile of 100 scrabble tiles, the probability of getting a “z” is 1 “by chance” • Thus, a p of 0.05 means that 95% of the time or 95/100 you will not get a “z” if there were a random mix of tiles with only one z

  39. Risk Factors for SSI • Patient-associated risk factors identified by studies in Malaysia and Vietnam 1. Praveen S et al. Asian J Surg 2009. 32(1):59-63.2. Yong KS, et al. Med J Malays 2001. 56 Suppl C:57-60. 3. Nguyen D et al. Infect Control Hosp Epidemiol 2001. 22(8):485-492. 4. Sohn AH et al. Infect Control Hosp Epidemiol 2002. 23(7):382-387. 5. Thu LTA et al. J Hosp Infect 2005. 60(4):360-367. MEDICAL

  40. Surgical site infection • SSI classification by surgical procedure 1 2 3 4 5 6 7 8 1. Duerink DO et al. J Hosp Infect 2006. 62(2):219-229.2. Sohn AH et al. Infect Control Hosp Epidemiol 2002. 23(7):382-387. 3. Praveen S et al. Asian J Surg 2009. 32(1):59-63. 4. Dhillon KS et al. Med J Malays 1995. 50(3):237-240. 5. Syahrizal AB et al. Med J Malays 2001. 56 Suppl D:5-8. 6. Yang K et al. J Arthroplasty 2001. 16(1):102-106. 7. Kehachindawat P et al. J Med Assoc Thai 2007;90(7):1356-62. 8. Thu LTA et al. Infect Control Hosp Epidemiol 2006. 27(8):855-862. MEDICAL

  41. Incidence of ssi • Gastrointestinal surgery • Incidence of SSI: 4 – 56% • Mahadeva S et al. Int J Clin Pract 2009. 63(5):760-765. • Thambidorai CR et al. Singapore Med J 2008. 49(12):994-997. MEDICAL

  42. Incidence of ssi • Orthopaedic surgery • Incidence of SSI: 4 – 15% • Dhillon KS et al. Med J Malays 1995. 50(3):237-240. • Syahrizal AB et al. Med J Malays 2001. 56 Suppl D:5-8. • Tay BH et al. Med J Malays 2000. 55 Suppl C:74-85. MEDICAL

  43. Incidence of ssi • Gynaecology & Obstetrics surgery • Incidence of SSI: 2 – 26% • Huam SH et al. Med J Malays 1997. 52(1):3-7. • Ramli R et al. Int Med J 2009. 16(4):279-282. MEDICAL

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