Table 3.
Outcomes of Three Rounds of Annual Low-Dose CT Screening, According to Risk Quintile.*
| Quintile of 5-Year Risk of Lung-Cancer Death | Participants | Lung-Cancer Cases | Lung-Cancer Deaths | Positive Screening Results | Number of False Positives per Prevented Lung-Cancer Death† | Number Needed to Screen†‡ | |||
|---|---|---|---|---|---|---|---|---|---|
| Total No. | Stage I† | Total No. | Prevented† | Total No. | False Positive†§ | ||||
| no. (%) | no. (%) | no. (%) | no. (%) | ||||||
| All quintiles | 26,604 (100) | 1083 | 530 (48.9) | 354 | 88 (24.9) | 10,151 | 9484 (93.4) | 108 | 302 |
| Quintile 1: 0.15–0.55% | 5,276 (19.8) | 71 | 40 (56.3) | 20 | 1 (5.0) | 1,699 | 1648 (97.0) | 1648 | 5276 |
| Quintile 2: 0.56–0.84% | 5,310 (20.0) | 105 | 59 (56.2) | 35 | 10 (28.6) | 1,879 | 1806 (96.1) | 181 | 531 |
| Quintile 3: 0.85–1.23% | 5,396 (20.3) | 182 | 84 (46.2) | 45 | 13 (28.9) | 2,024 | 1911 (94.4) | 147 | 415 |
| Quintile 4: 1.24–2.00% | 5,314 (20.0) | 263 | 132 (50.2) | 73 | 31 (42.5) | 2,123 | 1973 (92.9) | 64 | 171 |
| Quintile 5: >2.00% | 5,308 (20.0) | 462 | 215 (46.5) | 181 | 33 (18.2) | 2,426 | 2146 (88.5) | 65 | 161 |
*
The tabulated outcomes include all three rounds of low-dose CT screening and all events that occurred through January 15, 2009.
†
P<0.05 by means of a linear test of trend in continuous outcomes.
‡
The number needed to screen is the number of participants in the CT group divided by the number of lung-cancer deaths prevented by low-dose CT screening.
§
The number of participants with positive screening results includes all those with any positive result during the trial. P<0.05 by means of the Cochran–Armitage test of trend in proportions.