Table 3.
Population attributable fraction and number needed to prevent for modifiable risk factors for incident kidney stones
| HPFS | NHS I | NHS II | ||||
|---|---|---|---|---|---|---|
|
| ||||||
| Est. | 95% CI | Est. | 95% CI | Est. | 95% CI | |
|
| ||||||
| Higher BMI | ||||||
| - PAF % | 14.0 | 8.4, 18.9 | 21.8 | 16.7, 26.3 | 18.9 | 15.5, 22.2 |
| - NNTP | 115 | 85, 182 | 164 | 134, 213 | 112 | 94, 137 |
|
| ||||||
| Lower fluid intake | ||||||
| - PAF % | 26.0 | 20.8, 30.7 | 18.1 | 11.9, 23.3 | 16.8 | 12.8, 20.5 |
| - NNTP | 67 | 55, 85 | 164 | 129, 228 | 109 | 90, 139 |
|
| ||||||
| Lower DASH-style diet | ||||||
| - PAF % | 20.3 | 9.2, 30.0 | 17.6 | 5.2, 28.0 | 17.0 | 7.9, 25.2 |
| - NNTP | 148 | 101, 278 | 371 | 239, 910 | 233 | 162, 417 |
|
| ||||||
| Lower dietary calcium intake | ||||||
| - PAF % | 8.2 | 0, 18.8 | 11.2 | 0, 22.7 | 11.8 | 2.1, 20.1 |
| - NNTP | 358 | 162, NE | 556 | 295, 10,001 | 345 | 205, 1,001 |
|
| ||||||
| Higher SSB intake | ||||||
| - PAF % | 7.5 | 4.1, 10.5 | 4.4 | 1.2, 7.3 | 9.1 | 6.3, 11.6 |
| - NNTP | 117 | 84, 193 | 323 | 205, 770 | 150 | 117, 209 |
|
| ||||||
| Summary | ||||||
| - PAF % | 57.0 | 34.2, 71.4 | 55.2 | 29.7, 70.9 | 55.1 | 37.8, 67.3 |
| - NNTP | 19 | 16, 23 | 37 | 32, 45 | 24 | 21, 27 |
BMI, body mass index; CI, confidence interval; HPFS, Health Professionals Follow-up Study; NHS, Nurses’ Health Study; NNTP, number needed to prevent over 10 years; PAF, attributable fraction; SSB, sugar-sweetened beverages. For some risk factors with non-positive incidence rate ratios the NNTP was not estimable (NE)