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Four hundred and thirteen patients infected with HTLV-1 were included comprising 246
ACs and 167 SPs. Of the 167 SPs: 54 had ATLL; 95 HAM/TSP; 11 HAID and 7 strongyloidiasis
(Fig. 1). Fourteen (3.4 %), were found on pulmonary CT to have previously undiagnosed bronchiectasis.

Fig. 1. Flow diagram demonstrating the breakdown of the HTLV-1 cohort into symptomatic patients
and asymptomatic carriers

Although the majority of all subjects were of African/Afro-Caribbean origin (300/413,
72.6 %), SPs were significantly more likely to be of African/Afro-Caribbean ethnicity
(139/167, 83.2 %) than the ACs (161/246, 65.5 %, p??0.0001) (Table 1) and this applied across all the symptomatic subgroups: HAM/TSP 74/95 (77.9 %); ATLL
48/54 (88.9 %); Strongyloidiasis 7/7 (100 %); HAID 10/11 (91 %). SPs were older than
ACs (median age 54 vs. 44 years; p??0.0001) but there was no difference in the time
since HTLV-1 was diagnosed (i.e. duration of follow-up from first diagnosis; median
years in the SP 7.7 years; AC 7 years). There were fewer females in the AC group (63:183)
with a male to female ratio of 1:2.9 compared with 1:2.3 among the SPs (51:116) but
this was not significant (p?=?0.27).

Table 1. Characteristics of the HTLV-1 cohort and the indications for CT imaging

HTLV-1 VL, which was available for 167 SPs and 234 ACs, was significantly higher in
SPs (median HTLV VL 15.9 % 95 % CI 13.7 – 20) compared with ACs (median 1.25 %; 95 %
CI 0.82 – 1.69, p 0.0001). HTLV-1 VL among non-HAM/TSP SPs was higher still (median
21.6 %, non-HAM/TSP vs. AC; p?=?0.0001). The median VLs in the different SP groups
were: HAM/TSP 14 %, HAID 8.5 %, ATLL 29.3 % and Strongyloidiasis 20.6 % (Table 1).

Thirty four of 246 ACs and 30/167 SPs had a CT chest. Of the CT scans performed, 4/34
(11.7 %) in the AC group and 10/30 (33.3 %) in the SP group were high resolution CTs.
(HRCTs). The reasons for CT imaging were productive cough +/- recurrent infection
(50 % ACs vs. 50 % SPs), weight loss (26.5 % ACs vs. 23.3 % SPs), suspected malignancy
(23.5 % ACs vs. 6.7 % SPs) or an abnormal chest X-ray (SPs 16.7 %). The indication
for CT was unclear in 3.3 % SPs. The indications for HRCT was productive cough +/-
recurrent infection. The time from HTLV-1 diagnosis to imaging was on average 2.5 years
in ACs and 2 years in SPs (Table 1). Out of the total 64 patients that underwent CT imaging, 13 were Caucasian (13/90,
14 %) and 51 were Afro-Caribbean (51/300, 17 %).

Fourteen patients were newly diagnosed with bronchiectasis based on HRCT, (indications
detailed in Table 1): 1/246 AC (0.4 %) and 13/167 SPs (2 with HAID, 1 with ATLL, 10 with HAM/TSP) (7.8 %,
RR 19.2 95 % CI 2.5-14.5, p?=?0.004). Bronchiectasis was more common in those with
HAM/TSP compared to non-HAM/TSP patients (10/95 vs. 4/318, RR 8.4 95 % CI 2.7-26.1,
p?=?0.0002). None of our patients had a history of significant childhood infections
as per the patient or their health records. We thereby did not identify the other
causes of bronchiectasis including congenital conditions, tuberculosis, exposure to
chemical irritant or childhood infections. There were also no documented or clinical
features to suggest a diagnosis of bronchiectasis at or prior to the diagnosis of
HTLV-1 infection as per the patient or their health records. We did not exclude alpha-1
antitrypsin deficiency or autoimmune conditions however our patients had no other
clinical symptoms or signs to suggest these conditions. There was also no history
of organ failure or myocardial disease. All of our patients with bronchiectasis were
non-smokers. Through detailed history obtained from the patients and their health
records, they were diagnosed with bronchiectasis 1-3 years following their initial
HTLV-1 diagnosis and hence at least 1-3 years from any initial symptoms of HTLV-1
infection.

The characteristics of the patients with bronchiectasis are summarised in Table 2. The median HTLV-1 VL at the time of diagnosis of bronchiectasis was 25.2 % in the
SPs and 3.1 % in the solitary AC. Although higher, the median VL in HAM/TSP patients
with bronchiectasis was not significantly different from the remaining HAM/TSP patients
(25.2 % vs. 14 %, p?=?0.72). Bronchiectasis was more common amongst Caucasians (6.7 %;
6/20 SPs 0/70 ACs) than African/Afro-Caribbean (2.0 %; 5/137 SPs 1/163 ACs, Fisher’s
exact test p?=?0.01). The relative risk of bronchiectasis from not being African/Afro-Caribbean
was 3.45 (1.2-9.7, p?=?0.02). There was no significant difference in age at presentation
to the HTLV clinic diagnosis of HTLV-1 between SPs with and without bronchiectasis
(median 59.3 vs. 53.9 years, p?=?0.43) nor between the patients with HAM/TSP with
and without bronchiectasis (median 59.5 vs. 54.7 years, p?=?0.48).

Table 2. Characteristics of the HTLV-1 patients with a formal diagnosis of bronchiectasis

In the multivariate analysis disease state (p??0.001) and ethnicity (p?=?0.02) but
not age, gender or HTLV-1 VL were independent predictors for bronchiectasis.