Table 2 Search strategy for retrieval of relevant articles from multiple databases

MEDLINE n = 401

1. Opioid-related disorders/dt, rh, th [Drug Therapy, Rehabilitation, Therapy]

2. Opiate substitution treatment/

3. Methadone/

4. Sex Characteristics/

5. sex differences.m_titl.

6. gender differences.m_titl.

7. sex.m_titl.

8. male.m_titl.

9. female.m_titl.

10. men.m_titl.

11. women.m_titl.

12. 1 or 2 or 3

13. 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11

14. 12 and 13

15. limit 14 to humans

EMBASE n = 180

1. Opioid-related disorders/dt, rh, th [Drug Therapy, Rehabilitation, Therapy]

2. Opiate substitution treatment/

3. Methadone/

4. Sex Characteristics/

5. sex differences.m_titl.

6. gender differences.m_titl.

7. sex.m_titl.

8. male.m_titl.

9. female.m_titl.

10. men.m_titl.

11. women.m_titl.

12. 1 or 2 or 3

13. 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11

14. 12 and 13

15. limit 14 to humans

PsycINFO n = 241

1. exp Methadone Maintenance/ or exp Methadone/

2. exp Human Sex Differences/

3. sex.m_titl.

4. male.m_titl.

5. female.m_titl.

6. men.m_titl.

7. women.m_titl.

8. 2 or 3 or 4 or 5 or 6 or 7

9. 1 and 8

10. limit 9 to humans

CINAHL n = 23

1. Opioid abuse (TX All Text)

2. Methadone (TX All Text)

3. Methadone treatment programs (MJ Word in Major Subject Heading)

4. Gender differences (TX All Text)

5. Sex differences

6. 1 or 2 or 3 and 4 or 5

7. limit 6 to human