title: Evaluating the accuracy of sampling to estimate central line-days: simplification of the National Healthcare Safety Network surveillance methods.
abstract: OBJECTIVE
  To evaluate the accuracy of weekly sampling of central line-associated bloodstream infection (CLABSI) denominator data to estimate central line-days (CLDs).
  
  
  METHODS
  Obtained CLABSI denominator logs showing daily counts of patient-days and CLD for 6-12 consecutive months from participants and CLABSI numerators and facility and location characteristics from the National Healthcare Safety Network (NHSN).
  
  
  METHODS
  Convenience sample of 119 inpatient locations in 63 acute care facilities within 9 states participating in the Emerging Infections Program.
  
  
  METHODS
  Actual CLD and estimated CLD obtained from sampling denominator data on all single-day and 2-day (day-pair) samples were compared by assessing the distributions of the CLD percentage error. Facility and location characteristics associated with increased precision of estimated CLD were assessed. The impact of using estimated CLD to calculate CLABSI rates was evaluated by measuring the change in CLABSI decile ranking.
  
  
  RESULTS
  The distribution of CLD percentage error varied by the day and number of days sampled. On average, day-pair samples provided more accurate estimates than did single-day samples. For several day-pair samples, approximately 90% of locations had CLD percentage error of less than or equal to ±5%. A lower number of CLD per month was most significantly associated with poor precision in estimated CLD. Most locations experienced no change in CLABSI decile ranking, and no location's CLABSI ranking changed by more than 2 deciles.
  
  
  CONCLUSIONS
  Sampling to obtain estimated CLD is a valid alternative to daily data collection for a large proportion of locations. Development of a sampling guideline for NHSN users is underway.
authors: Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA. ndthompson@cdc.gov
authors: Nicola D
authors: ND
authors: Thompson
authors: Jonathan R
authors: JR
authors: Edwards
authors: Wendy
authors: W
authors: Bamberg
authors: Zintars G
authors: ZG
authors: Beldavs
authors: Ghinwa
authors: G
authors: Dumyati
authors: Deborah
authors: D
authors: Godine
authors: Meghan
authors: M
authors: Maloney
authors: Marion
authors: M
authors: Kainer
authors: Susan
authors: S
authors: Ray
authors: Deborah
authors: D
authors: Thompson
authors: Lucy
authors: L
authors: Wilson
authors: Shelley S
authors: SS
authors: Magill
mesh_terms: D062905:Central Venous Catheters / Q000009:adverse effects*; D003428:Cross Infection / Q000453:epidemiology* / Q000209:etiology; D019538:Health Care Surveys / Q000706:statistics & numerical data*; D006801:Humans; D011159:Population Surveillance; D018805:Sepsis / Q000453:epidemiology* / Q000209:etiology; D013997:Time Factors; D014481:United States / Q000453:epidemiology