Table 2. Factors explaining variation in discharge at scene rates.
| Variable | 9 ambulance services (with skill-mix data) | 10 ambulance services (no skill-mix data) | ||||||
|---|---|---|---|---|---|---|---|---|
| Patient-level | No of calls in denominator | No of calls resulting in discharge at scene | Unadjusted Odds Ratio+ (95% CI) |
Adjusted Odds Ratio (95% CI) |
P-Value | Unadjusted Odds Ratio+ (95% CI) |
Adjusted Odds Ratio (95% CI) |
P-Value |
| Age group | ||||||||
| 0–2 | 13,116 | 2,982 | 1 | 1 | - | 1 | 1 | - |
| 3–10 | 9,204 | 2,523 | 1.30 (1.22, 1.37) | 1.35 (1.27, 1.44) | <0.001 | 1.29 (1.22, 1.37) | 1.35 (1.27, 1.43) | <0.001 |
| 11–20 | 24,133 | 7,764 | 1.60 (1.53, 1.68) | 1.66 (1.58, 1.75) | <0.001 | 1.60 (1.53, 1.67) | 1.66 (1.58, 1.74) | <0.001 |
| 21–30 | 36,413 | 12,453 | 1.82 (1.75, 1.90) | 1.91 (1.82, 2.00) | <0.001 | 1.81 (1.73, 1.88) | 1.89 (1.81, 1.98) | <0.001 |
| 31–40 | 29,271 | 9,345 | 1.66 (1.59, 1.73) | 1.76 (1.68, 1.84) | <0.001 | 1.65 (1.58, 1.72) | 1.75 (1.67, 1.83) | <0.001 |
| 41–50 | 31,789 | 9,722 | 1.53 (1.46, 1.59) | 1.63 (1.55, 1.71) | <0.001 | 1.52 (1.46, 1.58) | 1.62 (1.55, 1.70) | <0.001 |
| 51–60 | 30,517 | 9,214 | 1.49 (1.43, 1.56) | 1.60 (1.52, 1.68) | <0.001 | 1.47 (1.41, 1.54) | 1.58 (1.51, 1.66) | <0.001 |
| 61–70 | 35,076 | 10,632 | 1.46 (1.40, 1.53) | 1.52 (1.45, 1.60) | <0.001 | 1.44 (1.38, 1.50) | 1.50 (1.44, 1.58) | <0.001 |
| 71–80 | 50,162 | 16,039 | 1.57 (1.51, 1.63) | 1.54 (1.47, 1.62) | <0.001 | 1.53 (1.47, 1.60) | 1.52 (1.45, 1.59) | <0.001 |
| 81–90 | 61,972 | 22,920 | 1.91 (1.84, 1.99) | 1.75 (1.67, 1.83) | <0.001 | 1.88 (1.81, 1.95) | 1.73 (1.66, 1.81) | <0.001 |
| > 90 | 22,222 | 9,248 | 2.29 (2.19, 2.39) | 1.99 (1.89, 2.09) | <0.001 | 2.25 (2.15, 2.35) | 1.97 (1.87, 2.07) | <0.001 |
| Sex | ||||||||
| Female | 163,599 | 52,053 | 1 | 1 | - | 1 | 1 | - |
| Male | 180,276 | 60,789 | 1.08 (1.06, 1.10) | 1.02 (1.00, 1.03) | 0.034 | 1.07 (1.06, 1.09) | 1.01 (1.00, 1.03) | 0.064 |
| Time of call | ||||||||
| Out of Hours | 224,933 | 75,996 | 1 | 1 | - | 1 | 1 | - |
| In Hours | 118,942 | 36,846 | 0.87 (0.85, 0.88) | 0.87 (0.85, 0.88) | <0.001 | 0.87 (0.85, 0.88) | 0.87 (0.86, 0.88) | <0.001 |
| Reason for call | ||||||||
| Falls | 58,411 | 25,828 | 1 | 1 | - | 1 | 1 | - |
| Abdominal Pain | 8,321 | 2,046 | 0.36 (0.35, 0.38) | 0.34 (0.32, 0.36) | <0.001 | 0.36 (0.35, 0.38) | 0.34 (0.32, 0.36) | <0.001 |
| Breathing difficulties | 43,341 | 11,729 | 0.49 (0.48, 0.50) | 0.62 (0.60, 0.63) | <0.001 | 0.49 (0.48, 0.51) | 0.62 (0.60, 0.63) | <0.001 |
| Cardiovascular | 58,189 | 13,040 | 0.37 (0.36, 0.38) | 0.46 (0.45, 0.48) | <0.001 | 0.37 (0.36, 0.38) | 0.46 (0.45, 0.47) | <0.001 |
| Fitting | 16,625 | 4,766 | 0.53 (0.51, 0.55) | 0.64 (0.62, 0.67) | <0.001 | 0.54 (0.52, 0.56) | 0.65 (0.62, 0.67) | <0.001 |
| Injury | 44,616 | 14,099 | 0.53 (0.52, 0.55) | 0.55 (0.54, 0.57) | <0.001 | 0.54 (0.53, 0.55) | 0.56 (0.55, 0.58) | <0.001 |
| Psychiatric | 9,227 | 3,293 | 0.74 (0.70, 0.77) | 0.74 (0.71, 0.78) | <0.001 | 0.74 (0.71, 0.77) | 0.74 (0.70, 0.77) | <0.001 |
| Sick or Unconscious | 52,478 | 17,063 | 0.63 (0.61, 0.64) | 0.71 (0.69, 0.72) | <0.001 | 0.63 (0.61, 0.64) | 0.70 (0.68, 0.72) | <0.001 |
| Other | 52,667 | 20,978 | 0.70 (0.69, 0.72) | 0.77 (0.75, 0.80) | <0.001 | 0.67 (0.66, 0.69) | 0.74 (0.73, 0.76) | <0.001 |
| Urgency Level | ||||||||
| Red 1 & 2 (emergency) | 167,581 | 45,759 | 1 | 1 | - | 1 | 1 | - |
| Green 1 & 2 (urgent) | 139,292 | 50,417 | 1.45 (1.43, 1.48) | 1.25 (1.23, 1.27) | <0.001 | 1.44 (1.42, 1.47) | 1.24 (1.22, 1.26) | <0.001 |
| Green 3 & 4 (low acuity) | 37,002 | 16,666 | 2.25 (2.20, 2.30) | 1.90 (1.86, 1.95) | <0.001 | 2.21(2.16, 2.26) | 1.87 (1.82, 1.91) | <0.001 |
| Source of call | ||||||||
| 999 | 336,915 | 109,995 | 1 | 1 | - | 1 | 1 | - |
| NHS 111 | 6,960 | 2,847 | 1.33 (1.27, 1.40) | 1.46 (1.38, 1.53) | <0.001 | 1.35 (1.29, 1.41) | 1.43 (1.37, 1.50) | <0.001 |
| Skill-mix | ||||||||
| Paramedic | 278,804 | 88,851 | 1 | 1 | - | - | - | - |
| Paramedic with extended skills | 23,189 | 10,111 | 1.36 (1.33, 1.40) | 1.38 (1.34, 1.42) | <0.001 | - | - | - |
| Other | 41,882 | 13,880 | 1.00 (0.98, 1.03) | 0.96 (0.94, 0.99) | 0.002 | - | - | - |
| % severe long term illness | ||||||||
| Q1 (Lowest) | 68,123 | 25,529 | 1 | 1 | - | 1 | 1 | - |
| Q2 | 70,079 | 22,553 | 0.96 (0.94, 0.98) | 0.95 (0.93, 0.97) | <0.001 | 0.96 (0.94, 0.99) | 0.95 (0.93, 0.98) | <0.001 |
| Q3 | 70,302 | 23,443 | 1.01 (0.94, 0.98) | 0.99 (0.96, 1.01) | 0.301 | 1.00 (0.98, 1.02) | 0.98 (0.96, 1.01) | 0.162 |
| Q4 | 70,225 | 23,334 | 1.00 (0.98, 1.03) | 0.97 (0.95, 1.00) | 0.039 | 1.00 (0.98, 1.03) | 0.97 (0.95, 1.00) | 0.048 |
| Q5 (Highest) | 65,146 | 20,983 | 1.05 (1.02, 1.08) | 1.01 (0.98, 1.04) | 0.368 | 1.04 (1.03, 1.07) | 1.00 (0.98, 1.03) | 0.798 |
| Indices of Multiple Deprivation | ||||||||
| Q5 (Least Deprived) | 44,140 | 15,378 | 1 | 1 | - | 1 | 1 | - |
| Q4 | 47,526 | 18,953 | 1.00 (0.98, 1.03) | 1.02 (0.99, 1.04) | 0.265 | 1.01 (0.99, 1.04) | 1.02 (0.99, 1.05) | 0.111 |
| Q3 | 46,859 | 22,807 | 1.03 (1.00, 1.05) | 1.04 (1.02, 1.07) | 0.002 | 1.03 (1.01, 1.06) | 1.05 (1.03, 1.08) | <0.001 |
| Q2 | 46,891 | 25,994 | 1.01 (0.99, 1.04) | 1.05 (1.02, 1.08) | 0.001 | 1.02 (1.00, 1.04) | 1.05 (1.03, 1.08) | <0.001 |
| Q1 (Most Deprived) | 44,163 | 29,710 | 0.99 (0.97, 1.02) | 1.05 (1.02, 1.08) | 0.002 | 1.00 (0.98, 1.03) | 1.05 (1.02, 1.08) | <0.001 |
| Ambulance service-level | ||||||||
| % calls attended by paramedics with extended skills | 343,875 | 112,842 | 1.04 (1.02, 1.08) | 1.05 (1.04, 1.07) | <0.001 | - | - | - |
| Organisational Motivation | ||||||||
| No view or mixed views | 260,597 | 85,540 | 1 | 1 | - | 1 | 1 | - |
| Opportunity | 36,625 | 16,925 | 1.74 (1.36, 2.23) | 0.80 (0.58, 1.11) | 0.176 | 1.88 (1.14, 3.09) | 1.38 (0.64, 2.97) | 0.407 |
| Risk Aversion | 46,653 | 10,377 | 0.58 (0.47, 0.72) | 0.78 (0.61, 0.98) | 0.036 | 0.63 (0.42, 0.93) | 0.70 (0.39, 1.29) | 0.255 |
| How extended paramedics are used | ||||||||
| No view or mixed views | 138,210 | 40,360 | 1 | 1 | - | 1 | 1 | - |
| In limited capacity | 153,896 | 49,926 | 1.16 (0.96, 1.41) | 1.06 (0.91, 1.24) | 0.460 | 1.29 (1.11, 1.49) | 1.19 (0.75, 1.87) | 0.460 |
| Established and valued | 51,769 | 22,556 | 1.71 (1.43, 2.05) | 1.82 (1.31, 2.34) | <0.001 | 1.95 (1.57, 2.42) | 1.52 (0.81, 2.84) | 0.191 |
+ these are odds ratios from a univariable logistic random effects model with ambulance service as a random intercept rather than a true unadjusted value (i.e. from a logistic regression model with no random effect)