Table 3.
Theoretical example of how changes in population and practice characteristics determined from the adjusted model would be expected to affect the number of patients receiving CXR in a year in a practice with 8000 patients, based on the mean CXR rate of 34 CXRs per 1000 patientsa
| Characteristic | Distribution of characteristics | CXRs, n (95% CI) | Difference in number of CXRs between 75th and 25th centile, n (95% CI) | |||
|---|---|---|---|---|---|---|
|
| ||||||
| Overall, mean (SD) | 25th centile | 75th centile | 25th centile | 75th centile | ||
| Practice population characteristics | ||||||
|
| ||||||
| Percentage of patients who are male | 50.1 (2.4) | 48.6 | 51.7 | 277 (273 to 281) | 265 (252 to 269) | −8 (−4 to −19) |
|
| ||||||
| Percentage of patients aged ≥65 years | 17.4 (6.8) | 12.8 | 22.0 | 226 (219 to 233) | 316 (309 to 323) | 97 (76 to 104) |
|
| ||||||
| Percentage of patients who are smokers | 17.1 (5.7) | 13.3 | 20.9 | 247 (241 to 253) | 295 (289 to 301) | 54 (35 to 61) |
|
| ||||||
| Percentage patients on heart failure registry | 0.9 (0.4) | 0.6 | 1.2 | 260 (253 to 267) | 282 (278 to 287) | 28 (14 to 32) |
|
| ||||||
| Ethnicity category, % | ||||||
| Mixed/multiple ethnic groups | 2.4 (1.8) | 1.2 | 3.6 | 260 (253 to 267) | 282 (275 to 289) | 29 (7 to 36) |
| Asian/Asian British | 9.3 (13.4) | 0.2 | 18.0 | 248 (243 to 253) | 294 (289 to 299) | 51 (35 to 56) |
| Black/African/Caribbean/Black British | 4.1 (6.7) | 0.00 | 8.6 | 280 (275 to 286) | 262 (256 to 268) | −13 (−7 to −30) |
|
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| General practice variables | ||||||
|
| ||||||
| Percentage who gave highest rating for general practice survey for: | ||||||
| Helpfulness of reception staff | 49.4 (13.1) | 40.5 | 58.2 | 279 (274 to 285) | 263 (257 to 268) | −11 (−6 to −27) |
| Ability to book appointment (access) | 27.6 (13.3) | 18.6 | 36.6 | 281 (276 to 285) | 263 (257 to 268) | −15 (−10 to −28) |
| Ability to see preferred GP (continuity) | 54.9 (8.8) | 48.9 | 60.8 | 261 (256 to 266) | 281 (276 to 286) | 25 (9 to 30) |
| Healthcare professional communication skills | 77.7 (8.6) | 71.9 | 83.5 | 264 (259 to 269) | 278 (273 to 283) | 19 (4 to 24) |
|
| ||||||
| Categorical variables | Difference in number of CXRs expected to result from theoretical change in deprivation from deprivation fifth 1, n (95% CI) | |||||
|
| ||||||
| Deprivation fifth 3 | 35 (19 to 50) | |||||
|
| ||||||
| Deprivation fifth 4 | 44 (26 to 61) | |||||
a
In the cases of variables for which moving from 25 th to 75 th centile would result in fewer CXRs, the example assumes that the variables follow a normal distribution. Only variables with effect sizes ≥1.04 or ≤0.96 (P<0.01) are included. CXR = chest X-ray. SD = standard deviation.