Estudiante 6

The results obtained from analysing data collected for evaluation of the performance of the “Questionnaire” screen are presented and described in this section. The results of statistically testing the “Questionnaire” screen in identifying hearing loss in excess of 50dBHL across four frequencies (0.5k, Ik, 2k and 4k) are also presented.

The evaluation of the performance of the “Questionnaire” screen against the pure-tone screen determined the validity of the screen in identifying permanent hearing impairment in children. The pure-tone screen was set at a cut off point of SOdBHL in identifying hearing loss in the better ear. The repeat “Questionnaire” and pure-tone screens were also analyzed and compared.

The “Questionnaire” screen’s sensitivity and specificity was worked out to determine its overall performance in identifying deaf children. The results comparing the “Questionnaire” screen with the pure-tone screen are presented in the subsequent tables.

a) Statistical testing of the performance of the “Questionnaire” screen

The Yates corrected statistics was used to test the significance of the “Questionnaire” screen in identifying hearing loss in children. The “Questionnaire” screen was compared with the pure-tone screen in identifying hearing loss in excess of 50dBHL of the better ear in 747 children screened by both protocols.

Tables 4.5-4.7 present the statistical tests for any difference between the “Questionnaire” screen and the pure-tone screen in identifying deaf children of ages 36-72 months. Table 4.5 shows the statistical significance test results of the performance of this screen among the three age groups (36-47 months; 48-59 months and 60-72 months) of the subjects. It

was hypothesised that there is no difference in the performance of the “Questionnaire” screen compared with the pure-tone screen in identifying deaf children.

The analysis excluded children who were either difficult to test or non co-operating as mentioned earlier on in the methods chapter. The pure-tone screen versus the “Questionnaire” screen results are presented in Tables 4.5 to 4.14 below.

Table 4.5 presents the analyses of the age distribution of the sample of the study screened by the “Questionnaire” screen compared with the pure-tone screen (n=747)

Table 4.5: Age groups of children screened by the first “Questionnaire” screen compared with the first pure-tone screen (n=747)

Age in Months Questionnaire screen Pure-tone Screen Total P-value Pass Difficulty testing

Fail Non co­

operating 36-47 Pass 135 61 2 12 210 Fail 2 10 17 3 32 0.71 Total 137 71 19 15 242 48-59 Pass 160 25 9 2 196 Fail 6 3 27 1 37 0.07 Total 166 28 36 3 233 60-72 Pass 209 7 8 2 226 Fail 16 - 28 2 46 0.27 Total 225 7 36 4 272 36-72 Pass 504 93 19 16 632 Fail 24 13 72 6 115 0.35 Total 528 106 91 22 747

Table 4.5 above presents the results obtained on 747 children by using both protocols, namely the “Questionnaire” and the pure-tone screens. The analysis was performed per age group. The results show that there were similarities (p>0.05) in the performance of the “Questionnaire” screen compared with the pure-tone screen in identifying the defined hearing loss in the study sample within the three age groups (36-47 months, 48-59 months and 60-72 months).

Nevertheless, in the age group 48-59 months results showed the “Questionnaire” screen performed at a borderline (0.05<p<0.10) compared to its performance in the other age

groups. This low performance of this screen in the age group 48-59 months compromised the effectiveness of the screen in identifying deaf children.

The next table presents the age distribution and the results of the istatistical tests performed on a random sample (n=131) selected for the repeat questionnaire screen compared with the pure-tone screen (see Table 4.6 below).

Table 4.6: Children using the repeat “Questionnaire” screen compared with the first pure- tone screen per age group (n=131)

Questionnaire screen Pure-tone Screen

Age in months Pass Difficulty

testing

Fail Non co­

operating Total P-value 36-47 Pass 25 11 1 3 40 0.07 Fail 1 - 5 1 7 Total 26 11 6 4 47 48-59 Pass 23 5 6 1 35 0.90 Fail - 1 5 - 6 Total 23 6 11 1 41 60-72 Pass 22 - 5 - 27 0.30 Fail 10 - 6 - 16 Total 32 - 11 - 43 36-72 Pass 75 16 7 4 102 0.42 Fail 6 1 21 1 29 Total 81 17 28 5 131

Table 4.6 above presents the results of statistically testing the data obtained on 131 children screened by both protocols. The analysis and statistical testing was performed on the three age groups (36-47 months, 48-59 months and 60-72 months) and the results show that there was no difference in the performance of the repeat “Questionnaire” screen compared with the pure-tone screen in all three age groups (p>0.05).

The further analysis of the results used a decision matrix model comparing the “Questionnaire” screen’s performances with the pure-tone screen as described in the methods chapter are presented in Tables 4.7 to 4.10.

Table 4.7: The “Questionnaire” compared with the pure-tone screening results (n=619)

Questionnaire screen Pure-tone screen Total

Pass Fail

Pass 504 19 523

Fail 24 72 96

Total 528 91 619

Table 4.8 shows that the “Questionnaire” screen’s performance was: the sensitivity (72/91) = 79% and specificity (504/528) = 96%; predictive value for positive (72/96) = 75%; predictive value for negative (504/523) = 96% and the overall performance (576/619) = 93% (P>0.05). This means that the questionnaire identified 93% of 619 children as having hearing/non hearing loss correctly in the study sample (n=619).

Tables 4.8 - 4.10 present the results of the performance of the “Questionnaire” screen in the three age groups (36-47 months, 48-59 months and 60-72 months)

Table 4.8: The 1®* “Questionnaire” compared with the pure-tone screening results for 3 6 - 4 7 months age group (n=156)

Questionnaire screen Pure-tone screen Total

Pass Fail

Pass 135 2 137

Fail 2 17 19

Total 137 19 156

Table 4.8 shows that the “Questionnaire” screen’s performance was: sensitivity (17/19) = 89% and specificity (135/137) = 99%; predictive value for positive (17/19) = 90%; predictive value for negative (135/137) = 99% and the overall performance (152/156) = 97% (P>0.05).

The first “Questionnaire” screen was compared with the first pure-tone screen for ages between 48 - 59 months (see Table 4.9).

Table 4.9: The 1®^ “Questionnaire” compared with the pure-tone screening results for 48 - 59 months age group (n=202)

Questionnaire screen Pure-tone screen Total

Pass Fail

Pass 160 9 169

Fail 6 27 33

Total 166 36 202

Table 4.9 shows that the “Questionnaire” screen’s performance was: sensitivity (27/36) = 75% and specificity (160/166) = 96%; predictive value for positive (27/33) = 82%; predictive value for negative (160/169) = 95% and the overall performance (187/202) = 93% (P>0.05).

The first “Questionnaire” screen was compared with the first pure-tone screen for ages between 60 - 72 months see Table 4.10 below.

Table 4.10: The “Questionnaire” compared with the 1®* pure-tone screening results for 6 0 - 7 2 months age group (n= 261)

Questionnaire Pure-tone screen Total

screen Pass Fail

Pass 209 8 217

Fail 16 28 44

Total 225 36 261

Table 4.10 shows that the “Questionnaire” screen’s performance was: sensitivity (28/36) = 77% and specificity (209/225) = 93%; predictive value for positive (28/44) = 64; predictive value for negative (209/217) = 96% and the overall performance (237/261) = 91% (P>0.05).

The performance of the first “Questionnaire” screen compared with the first pure-tone screen for ages: 36 - 47 months; 48 - 59 months and 60 - 72 months (range 36 - 72 months) is summarised in Table 4.11.

Table 4.11: The summary results o f the 1®^ “Questionnaire” screen compared with the 1®‘ pure-tone screen for ages 3 6 - 7 2 months

Sample (n=619)

Age in months Total number Sensitivity

% Specificity % 36-47 156 89 99 48-59 202 75 96 60-72 261 77 93 36-72 619 80 96

Table 4.11 shows that the “Questionnaire” screen’s performance for the three age groups is summarised as follows: the average sensitivity and specificity of the screen was 80% and 96% respectively.

Analysis of the repeat “Questionnaire” screen using the decision “matrix analysis” model described in the methods chapter, for test performance characteristics of the “Questionnaire” screen was used. The formulae of this model are used for calculation of the sensitivity and specificity; the predictive value for positive and predictive value for negative and the overall performance of the “Questionnaire” screen.

This model demonstrated how constant the screen was in identifying hearing loss in children in the three age groups (36-47 months, 48-59 months and 60-72 months). These results are presented in Tables 4 .13-4.16 below.

Table 4.12: The 2"^ “Questionnaire” compared with the 1®^ pure-tone screening results for 3 6 - 4 7 months age group (n=32)

Questionnaire Pure-tone screen Total

screen Pass Fail

Pass 25 1 26

Fail 1 5 6

Total 26 6 32

Table 4.12 shows that the repeat “Questionnaire” screen’s performance was: sensitivity (5/6) = 83% and specificity (25/26) = 96%; predictive value for positive (5/6) = 83%; predictive value for negative (25/26) = 96% and the overall performance (30/32) = 94% (P>0.05).

The second “Questionnaire” screen was compared with the first pure-tone screen for ages 48 - 59 months (see Table 4.13 below).

Table 4.13: The 2"^ “Questionnaire” compared with the 1®* pure-tone screening results for 48 - 59 months age group (n=34)

Questionnaire Pure-tone screen Total

screen Pass Fail

Pass 23 6 29

Fail - 5 5

Total 23 11 34

Table 4.13 shows that the “Questionnaire” screen’s performance was: sensitivity (5/11) = 46% and specificity (23/23) = 100%; predictive value for positive (5/5) = 100%; predictive value for negative (23/29) = 79% and the overall performance (28/34) = 82% (P>0.05).

The second “Questionnaire” screen was compared with the first pure-tone screen for ages 6 0 - 7 2 months (see Table 4.14 below).

Table 4.14: The 2"^ “Questionnaire” compared with the 1®^ pure-tone screening results for 60 - 72 months age group (n=43)

Questionnaire Pure-tone screen Total

screen Pass Fail

Pass 22 5 27

Fail 10 6 16

Total 32 11 43

Table 4.14 shows that the “Questionnaire” screen’s performance was: sensitivity (21/28) = 75% and specificity (75/81) = 93%; predictive value for positive (72/96) = 75%; predictive value for negative (504/523) = 96% and the overall performance (576/619) = 93% (P>0.05).

The performance of the second “Questionnaire” screen compared with the first pure-tone screen for ages: 36 - 47 months; 48 - 59 months and 60 - 72 months (range 36 - 72 months) is summarised in Table 4.15.

Table 4.15: The summary results o f the 2"^ “Questionnaire” screen compared with the T pure-tone screen for ages 3 6 - 7 2 months

Sample (n=109)

Age in months Total number Sensitivity

% Specificity % 36-47 32 83 96 48-59 34 46 100 60-72 43 75 93 36-72 109 68 96

The results of the performance of the repeat “Questionnaire” screen for all three age groups are summarised in Table 4.15 above as follows: sensitivity/specificity = 68% and 96% respectively.

The repeat “Questionnaire” screen results presented in Table 4.15 above are consistent with the earlier findings obtained from analysing the first “Questionnaire” screen data in Table 4.11.

The individual questions contained in the “Questionnaire” screen were also evaluated to determine each question’s performance in identifying deaf children in the sample group. These results are presented in subsequent sections.

4.1.3 Evaluation of the individual questions contained in the “Questionnaire”