| Variable | Abernethy [14] | Currow [24] | Johnson [17] | Oxberry [16] | Combined | ||
| Morphine | Oxycodone | ||||||
| Subjects | 47 | 85 | 10 | 35 | 35 | 213 | |
| Age | 73.1±9.5 (41–89) | 74.8±8.9 (51–88) | 66.2±11.6 (45–83) | 70.2±11.1 (41–89) | 70.2±11.1 (41–89) | 73.1±9.5 (41–89) | |
| Sex | |||||||
| Male | 35 (75) | 53 (62) | 10 (100) | 30 (86) | 30 (86) | 158 (74) | |
| Female | 13 (25) | 32 (38) | 0 (0) | 5 (14) | 5 (14) | 55 (26) | |
| Disease | |||||||
| Heart failure | 0 (0) | 3 (3.5) | 10 (100) | 35 (10) | 35 (10) | 83 (39) | |
| COPD | 42 (89) | 42 (49) | 0 (0) | 0 (0) | 0 (0) | 84 (39) | |
| MND | 1 (2) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 1 (<1) | |
| Cancer | 3 (6) | 24 (28) | 0 (0) | 0 (0) | 0 (0) | 27 (13) | |
| RLD | 2 (4) | 16 (19) | 0 (0) | 0 (0) | 0 (0) | 18 (8) | |
| Intensity of breathlessness | 42±23 (23–86) | 48±22 (1–85) | 35±25 (1–77) | 41±20 (10–90) | 48±22 (10–100) | 45±22 (1–100) | |
| Karnofsky performance scale | 63.6±16.4 (20–85) | 63.3±9.5 (40–80) | 67.6±3.9 (62–70) | 69.1±6.1 (60–80) | 69.4±6.1 (60–80) | 65.5±10.7 (20–85) | |
Data are presented as n, mean±sd (range) or n (%). COPD: chronic obstructive pulmonary disease; MND: motor neurone disease; RLD: restrictive lung disease.