Table 1

Univariate models of CDAD incidence, influenza virus, RSV, and antibiotic prescription time series during the period of January 2005 to December 2008, Québec, Canada

Time series (units)Monthly value (minimum-maximum)AR or MAaOrderbParameter (SE)P value
CDAD incidence (no. of cases/1,000 discharges)9.4 (5.9–19.3)AR11.305 (0.145)<0.0001
AR2−0.318 (0.146)0.0342
ARc120.308 (0.161)0.0621
Respiratory viruses (% positive tests)
    Influenza virus5 (0–25)AR10.960 (0.049)<0.0001
ARc120.331 (0.164)0.049
    RSV11 (1–40)AR10.972 (0.174)<0.0001
AR2−0.485 (0.165)0.0052
ARc120.421 (0.155)0.0096
MA1−0.529 (0.172)0.0036
Antibiotic prescriptions (DDD/100,000 inhabitants)
    Fluoroquinolones, all6,089 (4,698–8,281)AR10.923 (0.058)<0.0001
ARc120.838 (0.1224)<0.0001
        Ciprofloxacin3,351 (2,930–3,846)AR10.402 (0.146)0.0083
AR20.429 (0.146)0.0051
ARc120.739 (0.148)<0.0001
        Gatifloxacin130 (0–811)NAd
        Moxifloxacin1,701 (768–2,987)
        Gatifloxacin-moxifloxacineAR10.942 (0.050)<0.0001
ARc120.888 (0.113)<0.0001
        Levofloxacin627 (379–1,267)AR10.985 (0.031)<0.0001
MA12−0.491 (0.141)0.0016
        Ofloxacin179 (104–230)AR10.913 (0.086)<0.0001
MA40.415 (0.157)0.0115
        Norfloxacin100 (70–138)AR10.976 (0.045)<0.0001
ARc30.380 (0.152)0.0158
        Gemifloxacin1 (0–3)NAe
    Macrolides, all9,850 (5,601–5,539)AR10.937 (0.052)<0.0001
ARc120.860 (0.122)<0.0001
        Clarithromycin7,388 (3,837–1,648)AR10.934 (0.054)<0.0001
ARc120.893 (0.121)<0.0001
        Azithromycin1,932 (1,255–3,152)AR10.952 (0.046)<0.0001
ARc120.748 (0.136)<0.0001
        Erythromycin237 (173–339)AR10.994 (0.034)<0.0001
ARc120.424 (0.161)0.0117
        Telithromycin293 (1.4–941)NAe
  • a AR, autoregressive term, which represents the past values of the monthly incidence; MA, moving average term, which represents the past variance of the monthly observations.

  • b Delay in months before the effect is observed.

  • c Multiplicative.

  • d Data for the two drugs were merged because of discontinuation of gatifloxacin.

  • e Not analyzed because of discontinuation or limited use.