Table 3.
Estimated numbers of preventable TB cases and NNS and NNT for latent tuberculosis infection to prevent one case of TB in the first 5 years after arrival, among immigrants arriving in Norway 2008–2011
| Country of origin (WHO-estimated TB incidence rate per 100 000)* | Incident TB based on diagnosis ≥1 month after arrival | Incident TB based on diagnosis >6 months after arrival | ||||||
| Preventable TB†‡ | NNS‡§ | NNT, crude‡¶ | NNT, corrected‡** | Preventable TB†‡ | NNS‡§ | NNT, crude‡¶ | NNT, corrected‡** | |
| By country | ||||||||
| Myanmar (369) | 8 (12–6) | 111 (78–168) | 30 (22–46) | NA†† | 5 (7–3) | 181 (128–274) | 50 (35–76) | NA†† |
| Philippines (288) | 31 (44–20) | 218 (154–330) | 62 (44–94) | 59 (42–89) | 16 (23–11) | 419 (296–635) | 119 (84–180) | 104 (74–158) |
| Somalia (274) | 113 (159–74) | 66 (47–100) | 18 (13–27) | 13 (10–20) | 75 (107–50) | 99 (70–150) | 27 (19–41) | 17 (12–26) |
| Pakistan (270) | 6 (9–4) | 319 (225–484) | 85 (60–129) | 75 (53–113) | 4 (6–3) | 440 (311–668) | 117 (83–178) | 94 (67–143) |
| Ethiopia (207) | 20 (29–13) | 118 (83–179) | 32 (23–49) | 23 (16–34) | 16 (22–10) | 152 (108–231) | 42 (29–63) | 26 (19–40) |
| Afghanistan (189) | 20 (28–13) | 347 (245–526) | 72 (51–109) | 46 (32–69) | 15 (22–10) | 444 (313–673) | 92 (65–140) | 54 (38–82) |
| Thailand (171) | 9 (13–6) | 414 (292–628) | 83 (59–126) | 78 (55–119) | 7 (9–4) | 585 (413–887) | 117 (83–178) | 111 (79–169) |
| India (167) | 8 (12–6) | 334 (236–506) | 82 (58–124) | 75 (53–113) | 7 (10–5) | 396 (279–600) | 97 (68–147) | 89 (63–135) |
| Vietnam (140) | 6 (8–4) | 151 (107–229) | 30 (21–46) | 28 (20–42) | 1 (2–1) | 605 (427–917) | 120 (85–182) | 93 (66–141) |
| Eritrea (78) | 35 (50–23) | 194 (137–295) | 53 (38–81) | 43 (31–65) | 24 (34–16) | 286 (202–433) | 78 (55–119) | 56 (40–85) |
| Horn of Africa‡‡ | 168 (238–111) | 99 (70–151) | 27 (19–41) | 15 (11–23) | 115 (163–76) | 145 (103–220) | 40 (28–60) | 18 (13–27) |
| Countries grouped by estimated TB incidence rate* | ||||||||
| >150/100 000 | 241 (341–159) | 154 (109–234) | 32 (23–49) | 23 (16–35) | 160 (226–105) | 232 (164–352) | 48 (34–73) | 30 (21–45) |
| >200/100 000 | 193 (274–127) | 121 (85–183) | 28 (20–43) | 20 (15–31) | 124 (175–82) | 188 (133–286) | 44 (31–67) | 27 (19–41) |
| >200/100 000 §§ | 248 (351–164) | 149 (105–226) | 35 (25–53) | 23 (16–34) | 163 (231–108) | 227 (160–344) | 53 (38–81) | 29 (20–43) |
Estimates include TB occurring after 1 and 6 months and within the first 5 years following arrival in Norway, 2008–2011.
*From the 2014 WHO Global tuberculosis control report.6
†Number of patients with TB notified from screening cohorts, adjusted regarding diagnostic test sensitivity, treatment efficacy and adherence.
‡Using the point estimate with (range) of sensitivity, efficacy and adherence estimates.
§Ratio of the number of new arrivals to the number of preventable TB cases observed in Norway.
¶Ratio of the number of latent tuberculosis infection and preventable TB cases observed in Norway, that is, combined effect of emigration and risk of TB.
**1/risk of preventable TB for a person who stayed in Norway for 5 years, that is, corrected for the effect of emigration.
††Emigration is minimal (NA) since the majority arrived as refugees under the United Nations High Commissioner for Refugees and were granted residency prior to arrival.
‡‡Including Somalia, Eritrea and Ethiopia.
§§Includes countries with TB IRs >200/100 000 and Eritrea and Afghanistan (in line with current Norwegian guidelines).
NNS and NNT, numbers needed to screen and to treat to prevent one incident TB case within the first 5 years after arrival; TB, tuberculosis.