During the study period 152 patients developed a positive COVID RT-PCR test, which represented ~13% of patients being dialysed in SKC units, most of whom (81%) were male and mostly dialysing in-central dialysis facilities (95%), with 5% on PD at home. There were over 16 different nationalities represented in the group. The average age of COVID-19 PCR positive patients was 52 (SD 12) years, with range of 20-85 years. Around two thirds (64%) of patients had symptoms at the time of RT-PCR testing. Contact tracing was performed in all patients, and a COVID-19 positive close contact was identified in ~52% (79/152) of patients, suggesting the most likely acquisition route was in the community. In 36% (56/152), we could not connect the patient to any positive COVID-19 contacts within the dialysis unit (they did not dialyse in the same bay/shift or travel with any known positive Covid-19 patient), suggesting that they also likely to have contracted the virus outside the dialysis unit. We found 5% (7/152) who we traced to a possible contact within the dialysis unit and where we may have had a dialysis unit transmission event, as they dialysed in proximity to an index case within the unit (same bay/shift). A further 4% (6/152) cases were linked to a positive case by shared transport to the dialysis unit before we changed transport options for patients. A final 3% (4/152) appeared to have acquired during hospital admissions due to close contacts with positive cases in hospital.
Those patients whose presenting symptoms were recorded in the notes, reported fever and cough as the most common complaints (49% and 48% respectively). Other symptoms included dyspnoea (16%), myalgias (13%), gastrointestinal symptoms (6%) and loss of taste (1.3%) were reported in our patients. Significant associations with outcome are given in table 1. Most frequent comorbidities were hypertension (93%), diabetes (49%) and ischemic heart disease (30%). Risk assessment was performed at admission and patients were categorized into mild (68%), moderate (21%) and severe (11%) disease, based on clinical, laboratory and chest imaging findings. Around half the patients had an abnormal chest X ray (45%) or CT (52%).
Table 1: Clinical features of the dialysis patients who had positive COVID-PCR
|
Total
(n=152)
|
Alive
(n=138)
|
Died
(n=14)
|
P-value*
|
Demographics
|
|
|
|
|
Age, y
|
52.4 (12.1)
|
51.2 (11.3)
|
64.1 (3.5)
|
0.002
|
Male Sex, %
|
81 (123)
|
81 (112)
|
79 (11)
|
ns
|
|
|
|
|
|
Co-morbidities
|
|
|
|
|
Diabetes, % (n)
|
51 (78)
|
54 (75)
|
21 (3)
|
0.024
|
Cardiovascular disease, % (n)
|
70 (106)
|
72 (100)
|
43 (6)
|
0.032
|
Smoker, % (n)
|
43 (65)
|
41 (57)
|
57 (8)
|
ns
|
|
|
|
|
|
Presenting symptoms
|
|
|
|
|
Fever, % (n)
|
49 (74)
|
44 (61)
|
93 (13)
|
<0.001
|
Cough, % (n)
|
47 (72)
|
43 (60)
|
86 (12)
|
0.004
|
Dyspnoea, % (n)
|
16 (24)
|
12 (16)
|
57 (8)
|
<0.001
|
Myalgia, % (n)
|
13 (19)
|
12 (17)
|
14 (2)
|
ns
|
GI symptoms, % (n)
|
6 (9)
|
4 (6)
|
21 (3)
|
0.038
|
|
|
|
|
|
Disease severity
|
|
|
|
|
Mild, % (n)
|
68 (104)
|
75 (103)
|
7 (1)
|
|
Moderate, % (n)
|
21 (32)
|
20 (28)
|
29 (4)
|
|
Severe, % (n)
|
11 (16)
|
44 (7)
|
64 (9)
|
<0.001
|
|
|
|
|
|
Radiological findings
|
|
|
|
|
Abnormal chest x-ray, % (n)
|
45 (68)
|
40 (55)
|
93 (13)
|
<0.001
|
Abnormal chest CT, % (n)
|
53 (80)
|
49 (67)
|
93 (13)
|
0.001
|
*P-value determined using two-sample Wilcoxon rank-sum (Mann-Whitney) test for continuous variables and Fisher's exact test for categorical variables.
Different pharmacological combinations were used as recommended in the UAE national guideline and defined by disease severity, but treating physicians had flexibility to choose different drug regimens from the guidelines. Details of drugs used in mild, moderate and severe disease are given in figure 1. Associations of treatment and outcome are given are in table 2. All patients received prophylactic anticoagulation unless absolutely contraindicated.
Table 2: Drug treatments in patients who were treated for COVID
Drugs
|
Total
|
Alive
|
Dead
|
p- value
|
Hydroxychloroquine or chloroquine
|
60
|
50
|
10
|
ns
|
Favipiravir
|
101
|
100
|
1
|
p=0.28
|
Lopinavir and Ritonavir
|
13
|
6
|
7
|
ns
|
Camostat
|
48
|
48
|
0
|
ns
|
Azithromycin
|
7
|
4
|
3
|
p<0.002*
|
Steroid treatment
|
12
|
12
|
0
|
P<0.0001*
|
Tocilizumab
|
8
|
4
|
4
|
p<0.0001*
|
p<0.05 is significant
ICU admission was required in 13% of COVID-19 positive patients, 90% of these needed mechanical ventilation and 70% required continuous renal replacement therapy (as opposed to continuing with intermittent dialysis therapy). Despite ICU admissions 65% died. The overall mortality in our population was 9.2% (14/152), and median time from positive PCR to death in this group was 13 days [IQR 3-29].
Blood group was available in 146 of the 152 patients and blood groups are shown in table 3. In order to test the association with blood group and infection we compared observed blood group in infected individuals with quoted frequencies for the UAE (12) . When blood group O was compared with non-O groups, Fischer's exact test yielded p=0.03, with an OR 0.59 (95%CI 0.37 to 0.96), suggesting that blood group O may be associated with lower risks of infection. However, when we corrected this calculation for the expected for ethnicity (13) , this association was lost (table 3).
Table 3: Distribution of blood groups where known in study population
|
Quoted (12)(25)
|
UAE nationals (13)
|
Ethnically adjusted
|
Observed Frequency
|
O
|
48.4
|
56
|
41
|
28.1
|
A
|
24
|
26.2
|
25
|
17.1
|
B
|
22.9
|
14.2
|
27
|
18.5
|
AB
|
4.7
|
3.6
|
7
|
4.8
|
|
p=ns
|
p=ns
|
p=ns
|
|
|
|
|
|
|
O
|
48
|
56
|
41
|
36
|
non-O
|
51.6
|
44
|
59
|
64
|
|
|
|
|
|
|
p=0.03
|
p=0.006
|
p=ns
|
|
The median time to viral clearance as defined by a first positive to the first of two negative real time polymerase chain reaction (RT-PCR) was 15 days [IQR 6-26] in those that cleared the virus and survived. We noted that occasional patients had subsequently positive PCR result after two negatives, this was rarely more than one positive PCR and we did not count this as a relapse.
A subset of positive patients (87) underwent COVID-19 nucleocapsid IgG antibody testing and most (74% 64/87) were positive. In patients who were antibody positive the median time to viral clearance was 19 days (IQR 12-30). In contrast those in whom an IgG antibody was not detected had much shorter times from positive to first negative PCR (median 3 days [IQR 2-5]) p<0.0001, (figure 2). In patients who were not tested for IgG antibody the median positive time was 15 [IQR 6-29] days which was not significantly different to the IgG positive patients.
In the COVID-19 PCR positive patients we report no detectable antibodies in 26% (23/87) of those tested. The majority of these (78%) were asymptomatic (18/23) and most had a single positive PCR test before two negatives, with a median number of positive PCRs in this group was 1 (range1-2) and we cannot exclude these as false positive PCR tests (representing ~11% of all patients). 5 other interesting patients were those in whom the clinical presentations were consistent with COVID-19 disease and with a positive PCR test, but in whom antibodies did not develop. In this group 3 had a single positive PCR tests, but in two patients had 5 and 8 positive PCR results respectively making it highly probable they did indeed have COVID-19 infection but did not develop antibodies.
All staff were regularly screened and also tested if they were symptomatic, with 24 (~10%) clinical staff testing positive for COVID-19 PCR tests. Of these 63% (15/24) were symptomatic, but thankfully all staff recovered. Symptomatic staff had longer times 13 [IQR 10-22] days, from positive to two negative tests, compared with asymptomatic staff whose time to negativity was 2 [IQR0-8] days, p<0.001. We were interested in the asymptomatic group 38% (9/24). We do not know if these are false positive tests or viral acquisition and rapid clearance but they had a single positive test followed by two negative ones all within usually 96 hrs. All positive staff were immediately isolated, reviewed in hospital, and did not return to duty for at least 14 days after their second negative PCR. Many 46% (11/24) of the total positive clinical positive staff had close COVID contacts outside work which are likely to have been the cause of their acquisition of the virus or possibly the false positive test. In the rest (13) we cannot exclude a failure of PPE precautions, although 4 of these were in the asymptomatic probable false positive category, making the maximum number of likely transmission events to be ~9 if there was no community transmission in the study period.