Appendix 22. Assessment of adherence to TB treatment

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    Update: October 2023

     

    Assessment of adherence should be performed at each clinical visit or patient education session.

    The adherence assessment is performed as a short interview (± 5 minutes).

    For patients with adherence issues, take more time to understand the problems and try to resolve them in a manner adjusted to each individual.

    22.1 Self-administered treatment

    When treatment is self-administered, adherence is reported by the patient. To facilitate the assessment, various tools can be used. For example:

    Visual analogue scale

    Ask the patient to indicate on the ruler 0-10 how much prescribed TB drugs they have taken since the last visit.

    Explain that 0 corresponds to no doses taken at all, 5 to half of the doses taken and 10 to every single dose taken.

    For patients with a score less than 10, additional adherence support should be provided.

    Morisky medication adherence scale

    Ask the patient these 4 questions:
    1. Do you ever forget to take your medicines?
    2. Are you careless at times about taking your medicines? a Citation a. For example: not taking drugs as scheduled, or taking only a part of the prescribed dose, etc. 
    3. When you feel better, do you sometimes stop taking your medicines?
    4. If you feel worse when you take your medicines, do you sometimes stop taking them?

    Adherence is good if the patient answers “no” to all 4 questions. If the patient answers “yes” to one or more questions, additional adherence support should be provided.

    22.2 Directly observed treatment

    For patients who receive their treatment under supervision, the adherence rate or average DOT rate should be calculated and monitored at the end of each calendar month.  

    Adherence rate

    The adherence rate measures the patient’s adherence to the overall prescribed treatment:

     

    Number of prescribed days  –  (number of missed days + number of incomplete days)

    –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––  x 100

    Number of prescribed days

     

     

    Number of prescribed days: days in the month that the clinician prescribed TB treatment.

    Number of missed days: days in the month that the patient did not take any of the prescribed TB drugs.

    Number of incomplete days: days in the month that the patient took some prescribed TB drugs, but not all.

    DOT rate per drug 

    The DOT rate per drug measures patient’s adherence to each prescribed drug:

     

    Number of prescribed days for the drugs  –  number of missed days of the drug

    –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––  x 100

    Number of prescribed days for the drug      

    Average DOT rate

    The average DOT rate is the average of the DOT rate per drug.

     

     

    Box 22.1 – Example of the calculation of monthly adherence rate, DOT rate per drug and average DOT rate

     

    A patient is prescribed Bdq-Lzd-Lfx-Cs from the 10/09 (i.e. the number of prescribed days this month is 20). The patient did not take any treatment on the 20/09 and 21/09 (2 days) and did not take linezolid and cycloserine from the 25/09 to 29/09 (5 days).

     

    • Adherence rate for September: 20 – (2 + 5) ÷ 20 x 100 = 65%

     

    • DOT rate per drug for September:
      • for Bdq and Lfx: 20 – (2) ÷ 20 x 100 = 90%
      • for Lzd and Cs: 20 – (2 + 5) ÷ 20 x 100 = 65%

     

    • Average DOT rate for September: 90 + 90 + 65 + 65 ÷ 4 = 77.5%

     

    A goal of 100% adherence is ideal as higher treatment adherence results in better treatment outcomes. This patient has sub-optimal adherence. The reasons why the patient did not take the treatment (especially linezolid and cycloserine) should be explored and additional support should be provided.

     

    Footnotes
    • (a)For example: not taking drugs as scheduled, or taking only a part of the prescribed dose, etc.