Table 3. Cost-effectiveness analyses: costs and outcomes, complete cases sample (n = 117).
| Control (SE)(n = 49) | Intervention (SE)(n = 68) | Difference (95% CI) or ICER a | ||
| Costs prior to baseline (raw) | 9 755 (2 184) | 7 780 (976) | -1974 (-6 292, 2 344) | |
| Costs over study period (raw) | 9 309 (2 061) | 9 212 (1 234) | -97 (-4 600, 4 406) | |
| Continuous adherence outcome | Proportion adherent (raw) | 71.6 (21.7) | 85.8 (14.3) | 14.2 (7.6, 20.8) b |
| Proportion adherent (adjusted) | 73.4 (3) | 85.6 (2.9) | 12.2 (4.6, 19.8) c | |
| Costs over study period (adjusted) | 9 083 (1 931) | 9 681 (1 740) | 598 (-4 533, 5 730) | |
| ICER (20% increase adherence) | 982 (-8 020, 14 000) d | |||
| Binary adherence outcome | Adherence GTE 95% (raw) | 6.1 (24.2) | 29.4 (45.9) | 23.3 (9, 37.5) c |
| Proportion adherent (adjusted) | 4.9 (10.9) | 31.3 (10.3) | 26.5 (11.7, 41.2) b | |
| Costs over study period (adjusted) | 8 944 (1 954) | 9 724 (1 766) | 780 (-4 419, 5 979) | |
| ICER (achievement 'good' adherence) | 2 950 (-19 400, 27 800) d | |||
| Sensitivity | ||||
| Including costs of DNAs | Costs over study period (raw) | 10 410 (2 052) | 10 290 (1 288) | -120 (-4 694, 4 454) |
| Proportion adherent (adjusted) | 73.4 (2.9) | 85.6 (2.9) | 12.2 (4.7,19.8) c | |
| Costs over study period (adjusted) | 10 054 (1 949) | 10 486 (1 755) | 432 (-4 747,5 611) | |
| ICER (20% increase adherence) | 706 (-8 300, 13 540) | |||
| Unit costs: at 25% of estimate | Costs over study period (raw) | 6 830 (1 935) | 6 271 (1 169) | -559 (-4 803, 3 686) |
| Proportion adherent (adjusted) | 73.3 (3.0) | 85.7 (2.9) | 12.4 (4.8, 20) c | |
| Costs over study period (adjusted) | 6 390 (1 772) | 6 480 (1 577) | 90 (-4 593, 4 774) | |
| ICER (20% increase adherence) | 146 (-7 920, 11 160) | |||
| Unit costs: at 50% of estimate | ||||
| Costs over study period (raw) | 8 023 (1 968) | 7 611 (1 202) | -412 (-4 748, 3 923) | |
| Proportion adherent (adjusted) | 73.3 (2.9) | 85.7 (2.8) | 12.3 (4.8,19.9) c | |
| Costs over study period (adjusted) | 7 369 (1 833) | 7 663 (1 635) | 294 (-4 555, 5 144) | |
| ICER (20% increase adherence) | 476 (-7 900, 12 120) | |||
| Unit costs: at 150% of estimate | Costs over study period (raw) | 12 797 (2 158) | 12 970 (1 398) | 172 (-4 705, 5 050) |
| Proportion adherent (adjusted) | 73.5 (3) | 85.6 (2.9) | 12.1 (4.5, 19.7) c | |
| Costs over study period (adjusted) | 11 325 (2 075) | 12 397 (1 874) | 1 072 (-4 448, 6 592) | |
| ICER (20% increase adherence) | 1 770 (-7 880, 16 380) | |||
| Secondary outcomes | ||||
| Control (SE) (n = 41) | Intervention (SE) (n = 55) | Difference (95% CI) | ||
| Clinical Global Impression (binary) | Proportion improved (raw) | 40 (49.6) | 58.2 (49.8) | 18.2 (-2.3, 38.7) |
| Proportion improved (adjusted) | 43 (9.7) | 55.5 (9.1) | 12.5 (-12.3, 37.3) | |
| Costs over study period (adjusted) | 10 238 (2 053) | 8 905 (1 796) | -1 333 (-6 726, 4 061) | |
| Control (SE) | Intervention (SE) | Difference (95% CI) | ||
| Subjective Quality of Life (SQOL) | SQOL score (raw) (control n = 30; intervention n = 54) | 4.99 (0.96) | 5.18 (0.75) | 0.193 (-0.18, 0.57) |
| SQOL score (adjusted) (control n = 20; intervention n = 37) | 4.764 (2.587) | 5.462 (2.56) | 0.698 (0.239, 1.157) c | |
| Costs over study period (adjusted) (control n = 20; intervention n = 37) | 9 902 (2 990) | 7 824 (2 266) | -2 078 (-9 553, 5 397) |
ICER = incremental cost-effectiveness ratio; DNA = did not attend sessions with health professionals.
a ICER rounded to nearest 10.
b p<0.001.
c p<0.01.
d The negative lower limit of the ICER confidence interval indicates dominance (the intervention is less costly and more effective).