Table 1. Results of the National Lung Screening Trial (1).

	Low dose CT		Conventional chest radiography		Relative effect size	95% CI
	N	%	N	%
Participants	26722		26732
Compliance		95.0		93.0
Screening examinations	75126		73470
Positive results	18146	24.2	5043	6.9
False positive	17 497	96.4	4764	94.5
True positive	649	3.6	279	5.5
Conspicuous result without suspicion of malignancy	5622	7.5	1575	2.1
At least one positive result (proportion of participants)		39.1		16.0
Lung cancer diagnosed	1060		941
After positive result	649		279
After negative result	44		137
After end of study or no screening performed*1	367		525
Program sensitivity*2		94.1		67.9
Incidence of lung cancer (per 100000 person years)	645		572		1.13	1.03–1.23
Deaths (from any cause)	1877		2000
Relative reduction in overall mortality (%)					6.7	1.2–13.6
Unknown cause of death	12		9
Known cause of death	1865		1991
Lung cancer, incl. DCO	427	22.9	503	25.3
Other neoplasms	416	22.3	442	22.2
Cardiovascular diseases	486	26.1	470	23.6
Diseases of the respiratory tract	175	9.4	226	11.4
Treatment complications	12	0.6	7	0.4
Others	349	18.7	343	17.2
Lung cancer deaths, without DCO	356		443
Lung cancer mortality (per 100000), without DCO	247		309		0.80	0.73–0.93
Relative risk reduction (%)					20.0	6.8–26.7
Participants with at least one screening	26455		26232
Lung cancer deaths (without DCO)	346	1.3	425	1.6
Number needed to screen	320
Number needed to harm*3
Major complication	307–453
Intermediate complication	192–281
Minor complication	1406–2671
At least one complication	109–163
Death within 60 days of highly invasive procedure	1272–3815

^*1Altogether there were 3875 death certificates, 1877 in the low dose CT group and 1998 in the conventional radiography group; the cause of death was unknown in 12 and 7 persons respectively; the denominators for the percentages of causes of death relate to all deaths for which the cause was known, i.e., 1865 and 1991 deaths respectively; overall (low dose CT and conventional radiography) lung cancer was diagnosed 892 times, n=35 in participants who were not screened at all, n=802 in screened participants but after the end of the screening phase, and n=55 in persons who were The program scheduled for but had not yet undergone screening

^*2sensitivity for the first 3 years was calculated from the data of Patz et al. See (9).

^*3 eBox 3

CT, computed tomography; N, number; 95% CI, 95% confidence interval; DCO, death certificate only (deaths for which the death certificate is the only source of information); for definitions of major, intermediate, and minor complications, see eBox 2