A ‘missing not at random’ (MNAR) and ‘missing at random’ (MAR) growth model comparison with a buprenorphine/naloxone clinical trial

Authors

  • Sterling McPherson,

    Corresponding author
    1. College of Nursing, Washington State University, Spokane, WA, USA
    2. Department of Psychology, Washington State University, Pullman, WA, USA
    3. Program of Excellence in Addictions Research, Washington State University, Spokane, WA, USA
    4. Program for Rural Mental Health and Substance Abuse Treatment, Washington State University, Spokane, WA, USA
    5. Translational Addictions Research Center, Washington State University, Pullman, WA, USA
    • Correspondence to: Sterling McPherson, College of Nursing, Washington State University, PO Box 1495, SNRS 314C, Spokane, WA 99210-1495, USA. E-mail: smcpherson05@wsu.edu

    Search for more papers by this author
  • Celestina Barbosa-Leiker,

    1. College of Nursing, Washington State University, Spokane, WA, USA
    2. Department of Psychology, Washington State University, Pullman, WA, USA
    3. Program of Excellence in Addictions Research, Washington State University, Spokane, WA, USA
    4. Program for Rural Mental Health and Substance Abuse Treatment, Washington State University, Spokane, WA, USA
    5. Translational Addictions Research Center, Washington State University, Pullman, WA, USA
    Search for more papers by this author
  • Mary Rose Mamey,

    1. Department of Psychology, Washington State University, Pullman, WA, USA
    Search for more papers by this author
  • Michael McDonell,

    1. Department of Psychiatry and Behavioral Sciences, University of Washington School of Medicine, Seattle, WA, USA
    Search for more papers by this author
  • Craig K. Enders,

    1. Department of Psychology, Arizona State University, Tempe, AZ, USA
    Search for more papers by this author
  • John Roll

    1. College of Nursing, Washington State University, Spokane, WA, USA
    2. Department of Psychology, Washington State University, Pullman, WA, USA
    3. Program of Excellence in Addictions Research, Washington State University, Spokane, WA, USA
    4. Program for Rural Mental Health and Substance Abuse Treatment, Washington State University, Spokane, WA, USA
    5. Translational Addictions Research Center, Washington State University, Pullman, WA, USA
    6. Department of Psychiatry and Behavioral Sciences, University of Washington School of Medicine, Seattle, WA, USA
    Search for more papers by this author

Abstract

Aims

To compare three missing data strategies: (i) the latent growth model that assumes the data are missing at random (MAR) model; (ii) the Diggle–Kenward missing not at random (MNAR) model, where dropout is a function of previous/concurrent urinalysis (UA) submissions; and (iii) the Wu–Carroll MNAR model where dropout is a function of the growth factors.

Design 

Secondary data analysis of a National Drug Abuse Treatment Clinical Trials Network trial that examined a 7-day versus 28-day taper (i.e. stepwise decrease in buprenorphine/naloxone) on the likelihood of submitting an opioid-positive UA during treatment.

Setting

11 out-patient treatment settings in 10 US cities.

Participants

A total of 516 opioid-dependent participants.

Measurements

Opioid UAs provided across the 4-week treatment period.

Findings

The MAR model showed a significant effect (B = −0.45, P < 0.05) of trial arm on the opioid-positive UA slope (i.e. 28-day taper participants were less likely to submit a positive UA over time) with a small effect size (d = 0.20). The MNAR Diggle–Kenward model demonstrated a significant (B = −0.64, P < 0.01) effect of trial arm on the slope with a large effect size (d = 0.82). The MNAR Wu–Carroll model showed a significant (B = −0.41, P < 0.05) effect of trial arm on the UA slope that was relatively small (d = 0.31).

Conclusions

This performance comparison of three missing data strategies (latent growth model, Diggle–Kenward selection model, Wu–Carrol selection model) on sample data indicates a need for increased use of sensitivity analyses in clinical trial research. Given the potential sensitivity of the trial arm effect to missing data assumptions, it is critical for researchers to consider whether the assumptions associated with each model are defensible.

Ancillary