Values of NNTH for prolonged use of opioids after elective surgery
| Comparison | Definition of prolonged use of opioids | Adjusted RR (95% CI) | NNTH
(95% CI) |
| Tramadol alone vs other short-acting opioids | Additional opioid use* | 1.06 (1.00 to 1.13) | 373 (135 to 544) |
| Persistent opioid use† | 1.47 (1.25 to 1.69) | 272 (171 to 566) | |
| CONSORT definition of chronic opioid use‡ | 1.41 (1.08 to 1.75) | 952 (401 to 8400) | |
| Tramadol and short-acting opioids vs other short-acting opioids | Additional opioid use* | 1.05 (0.96 to 1.14) | 43 (32 to 64) |
| Persistent opioid use† | 1.04 (0.86 to 1.21) | 60 (47 to 79) | |
| CONSORT definition of chronic opioid use‡ | 1.40 (1.05 to 1.74) | 120 (86 to 179) | |
| Any long-acting opioid compared with other short-acting opioids | Additional opioid use* | 0.95 (0.87 to 1.03) | 36 (28 to 50) |
| Persistent opioid use† | 1.18 (1.02 to 1.35) | 31 (26 to 37) | |
| CONSORT definition of chronic opioid use‡ | 1.69 (1.36 to 2.02) | 54 (44 to 68) |
The statistically significant results are in bold.
Formulae for NNTH,7 calculated using Stata SE V.14.18
NNTH=1/(absolute increase in risk)
eg, NNTH=1/((1066/13 519)−(25 388/333 289))
NNTH=1/(0.0789−0.0762)
NNTH=1/0.0027
NNTH=373
eg, Stata code: bcii 1066 25388 12453 307901, level(95)
Stata output: Risk of improvement for control (p0): 0.076
Risk of improvement for intervention (p1): 0.079
Risk difference (p1−p0): 0.003
Newcombe method 10 95% CI −0.002 to 0.007
Number needed to treat (improvement): 373.433
Bender’s 95% CI 134.649 to544.013
*At least one opioid fill 90–180 days after surgery.
†Any span of opioid use starting in 180 days after surgery and lasting ≥90 days.
‡Opioid episode starting in 180 days after surgery that spans ≥90 days and includes either ≥10 opioid fills or ≥120 days’ supply of opioids.
CONSORT, Consortium to Study Opioid Risks and Trends; NNTH, number needed to harm; RR, risk ratio.