Does adherence to the Loeb minimum criteria reduce antibiotic prescribing rates in nursing homes?

The Loeb minimum criteria (LMC), developed by a 2001 consensus conference, are minimum standards for initiation of antibiotics in long term care settings, intended to reduce inappropriate prescribing. This study examined the relationship between nursing home prescriber adherence to the LMC and antibiotic prescribing rates, overall and for each of three specific conditions (urinary tract infections, respiratory infections, and skin and soft tissue infections).

We performed a cross-sectional analysis at the resident-day level. We estimated multivariate models adjusting for nursing home characteristics via multilevel Poisson regression, with robust standard errors to account for clustering of prescriptions within residents within nursing homes.

Data were collected through medical record abstraction in 12 North Carolina nursing homes between March and May 2011.

In total, we identified 3381 antibiotic prescriptions across the 3-month observation period, representing 110,810 nursing home resident-days. In addition, we performed chart audits for a random sample of 653 prescriptions for urinary tract, respiratory, and skin and soft tissue infections to create measures of LMC adherence.

The primary outcome was a count of prescriptions per resident per day, and the key explanatory variable was a nursing home-level estimate of the proportion of antibiotic prescriptions that adhered to the LMC.

Only 12.7% of prescriptions were classified as LMC adherent, although there was substantial variation across study nursing homes (range: 4.8% to 22.0%) and by infection type (1.9% adherence for respiratory infections, 10.2% for urinary tract infections, and 42.7% for skin and soft tissue infections). We found no statistically significant relationship between adherence to the LMC and total prescribing rates (IRR 1.00, 95% CI 0.98-1.03; P = .84). Similarly, there was no significant relationship between LMC adherence and prescribing rates for treating urinary tract infections (IRR 0.99, 95% CI 0.96-1.02; P = .49), respiratory infections (IRR 0.91, 95% CI 0.76-1.08; P = .28), or skin and soft tissue infections (IRR 0.99, 95% CI 0.98-1.01; P = .39) considered alone.

We found little evidence that prescribers in study nursing homes considered the LMC when making prescribing decisions. Further, we found no evidence that greater adherence to the LMC was associated with lower rates of antibiotic prescribing. Evidence-based guidelines for antibiotic initiation must be adopted more widely before any substantial gains from adherence are likely to be recognized.