Socio-demographic characteristics of the study participants
The mean ±SD age of study participants was 28.4 ±16.5 years; it ranged from 5 - 75 years with median age of 24 years. More than half (53.6%) of the participants were aged below 25 years, and females made 58.2% of the study population. 59.3% of the participants had only attained primary education as their highest level of education, about a third were living in a family with ≥7 people, 58.8% had no health insurance cover and majority of the patients were unemployed (75.7%). Table 1 summarizes the socio-demographic characteristics of the study participants.
Table 1. Socio-demographic characteristics of the study participants (N = 194)
Characteristic
|
Frequency
(n)
|
Percentage
(%)
|
Age groups (years)
≤ 25
26 – 45
>45
|
104
55
35
|
53.6
28.4
18.0
|
Sex
Males
Females
|
81
113
|
41.8
58.2
|
Marital status
Single
Married
Divorced
Widowed
|
65
111
7
11
|
33.5
57.2
3.6
5.7
|
Level of Education
No formal education
Primary
Secondary
University
|
10
115
48
21
|
5.2
59.3
24.7
10.8
|
Family size (number)
≤6 people
≥7 people
|
127
67
|
65.5
34.5
|
Mode of Payment
Insurance
Out of pocket
|
80
114
|
41.2
58.8
|
Average Family Income (TZS)
<70,000
70,000 – 310,000
>310,000
|
113
52
29
|
58.2
26.8
15.0
|
Employment Status
Employed
Unemployed
Retired
Student
|
30
147
7
10
|
15.5
75.7
3.6
5.2
|
TZS = Tanzanian Shillings
Clinical and other characteristics of the study participants
Most of the study participants (84.5%) were aware of their medical condition and they knew what they were suffering from. Slightly more than half (51%) of study participants knew about the need to take regular injections/medicine as prophylaxis, but only 17.5% knew the importance of the prophylaxis. Fifty-four (42.5%) participants were diagnosed within 1 year, while 32 (25.2%) were diagnosed between 1 year and 3 years and the rest of the study participants 41 (32.3%) had been diagnosed more than 3 years prior to the study. Furthermore, 98 (50.5%) participants had single valve diseases while the remaining 96 (59.5%) had multiple valvular lesions. Surgical intervention was done in 37 (19.1%) patients.
ARF prophylaxis status
Among 194 patients interviewed, 58 (29.9%) were on regular prophylaxis at the time of data collection, 39 (20.1%) had stopped prophylaxis, and 97 (50.0%) had never been on prophylaxis since diagnosis. Of the 58 patients that were on regular prophylaxis, 33 (56.9%) were on 4-weekly regime and the remaining 25 (43.1%) were on 3-weekly regime.
Throat colonization and antimicrobial susceptibility of GAS isolated from study participants
In the total study population, throat culture results of 25 patients were positive for GAS, giving GAS throat colonization rate of 12.9%. GAS isolated from the 25 patients were mostly susceptible to Benzathine Penicillin G (24/25, i.e. 96% susceptible), Ceftriaxone (24/25, i.e. 96% susceptible), and Clindamycin (24/25, i.e. 96% susceptible). GAS isolates were found to show highest resistance towards Vancomycin (5/25, i.e. 20% resistance) and Chloramphenicol (2/25, i.e. 8% resistance). There were also high intermediate susceptibilities towards most commonly used antimicrobial agents including Oxacillin (20%), Erythromycin (28%) and Co-trimoxazole (32%). Figure 1 shows the susceptibility patterns of GAS towards the 8 antibiotics that were tested. The negative numbers shown in figure 1 represent the number of isolates that were resistant to the respective antibiotics.
Factors associated with GAS throat colonization among study participants
Patients with positive throat culture did not differ from those with negative culture with regards to age distribution, gender, level of education, number of people in the household as well as family income, all p > 0.05 (Table 2). They also did not differ in terms of knowledge and understanding of importance of ARF prophylaxis, p > 0.05 for both (Table 2). Although not statistically significant, patients with positive culture had higher proportions of un-insured (68% versus 57.4%), unemployed (38% versus 22.5%), those unaware of their medical condition (24% versus 14.2%) as well as patients with multiple valve disease (60% versus 47.9%), (Table 2).
With regards to prophylaxis status, patients who had stopped prophylaxis had significantly higher proportion with positive cultures (26%) when compared to those that were on regular (10.3%) and those that had never started (9.3%), p = 0.029 (Table 2).
Table 2. Socio-demographic, clinical and other characteristics in relation to GAS throat colonization
Characteristic
|
Culture Negative
(n = 169)
|
Culture Positive
(n = 25)
|
p-value
|
Age <25 (years)
|
89 (52.7)
|
13 (52)
|
0.559
|
Female gender
|
97 (57.4)
|
16 (64)
|
0.345
|
Primary or less level of education
|
110 (65.1)
|
15 (60)
|
0.387
|
≥7 people in the household
|
59 (34.9)
|
8 (32)
|
0.483
|
Not insured
|
97 (57.4)
|
17 (68)
|
0.217
|
Family income TZS <70,000
|
97 (57.4)
|
16 (64)
|
0.345
|
Unemployed
|
38 (22.5)
|
8 (38)
|
0.211
|
Didn’t know about RHD suffering
|
24 (14.2)
|
6 (24)
|
0.165
|
Didn’t know about ARF prophylaxis
|
84 (49.7)
|
11 (44)
|
0.376
|
Didn’t know the importance of prophylaxis
|
139 (82.2)
|
21 (84)
|
0.545
|
Had surgical intervention
|
30 (17.7)
|
6 (24)
|
0.331
|
Had multiple valve disease
|
81 (47.9)
|
15 (60)
|
0.181
|
Prophylaxis status
On regular prophylaxis
Stopped prophylaxis
Never been on prophylaxis
|
52 (89.7)
29 (74.3)
88 (90.7)
|
6 (10.3)
10 (26)
9 (9.3)
|
0.029
|
TZS = Tanzanian Shillings; RHD = Rheumatic Heart Disease; ARF = Acute Rheumatic Fever.
Prophylaxis status and other factors that were weakly associated with culture positivity were entered into a logistic regression model to determine the factors that are independently associated with GAS culture positive results. Having stopped prophylaxis was the only factor that was independently associated with positive culture results in multivariate logistic regression analysis, OR (95% CI) = 3.26 (1.04 – 10.24), p = 0.043 (Table 3). Specifically, compared to patients on regular ARF prophylaxis, patients who stopped prophylaxis were 3.26 times more likely to have positive throat culture results independent of gender, disease awareness, insurance status, number of diseased valves or previous valvular surgery, (Table 3).
Table 3: Multivariate logistic regression analysis of factors associated with GAS colonization among RHD patients
Variable
|
Univariate analysis
|
Multivariate analysis
|
OR (95% CI)
|
p-value
|
OR (95% CI)
|
p-value
|
Female sex
|
1.32 (0.55 – 3.16)
|
0.533
|
1.31 (0.53 – 3.31)
|
0.547
|
Un-insured
|
1.58 (0.65 – 3.86)
|
0.318
|
1.62 (0.61 – 4.03)
|
0.348
|
Living >7 people in the household
|
0.88 (0.36 – 2.15)
|
0.775
|
0.73 (0.28 – 1.93)
|
0.524
|
Unaware of disease condition
|
1.91 (0.69 – 5.26)
|
0.212
|
2.42 (0.77 – 7.59)
|
0.129
|
Prophylaxis status
Regular on prophylaxis
Stopped prophylaxis
Never started
|
Reference
2.99 (0.99 – 9.06)
0.89 (0.30 – 2.63)
|
0.053
0.828
|
Reference
3.26 (1.04 – 10.24)
0.98 (0.32 – 3.02)
|
0.043
0.975
|
Multivalve disease
|
1.63 (0.69 – 3.83)
|
0.263
|
1.87 (0.74 – 4.67)
|
0.189
|
History of previous surgery
|
1.41 (0.52 – 3.81)
|
0.503
|
1.87 (0.62 – 5.59)
|
0.265
|