Table 4

Random coefficient for SLS COPD placed in distribution of random coefficients of local authorities from CPRD (self-controlled comparison within the trial before and during the trial period)

VariableCPRD-xGM 2.5th percentileCPRD-xGM median valueCPRD-xGM 97.5th percentileSLS COPD valueSLS COPD percentileUnusual flag
Count of AECOPD*†0.881.001.151.0264.17No
Count of strict definitionn of AECOPD*‡0.810.961.211.34100Yes
Number of days contact with primary care*0.971.071.191.0857.06No
Count of trial-related prescriptions§0.951.031.080.630Yes
Treatment switching¶**0.600.630.650.590.27Yes
  • For full definitions of above outcomes, see online supplementary appendix 1.

  • For Poisson models, the random intercepts represent relative rates; for logistic models, they represent ORs. SLS COPD is deemed unusual with respect to a particular variable if the random intercept for the SLS lies outside of the 2.5th–97.5th percentile range of the distribution of random intercepts of the local authorities in CPRD.

  • *Poisson model.

  • †AECOPD events were those that met any criteria from the validated algorithm.16

  • ‡The strict definition of AECOPD events was strictly codes for acute exacerbation of COPD.

  • §Prescription of any treatment counted as usual care in SLS COPD.

  • ¶Logistic model.

  • **Switching from one treatment class to another during follow-up.

  • AECOPD, acute exacerbations of COPD; COPD, chronic obstructive pulmonary disease; COPD, Salford Lung Study in chronic obstructive pulmonary disease; CPRD-xGM, Clinical Practice Research Datalink outside of Greater Manchester.