Study selection
A total of 6879 studies were identified using electronic searches (through Databases searching (n = 6867)) and other sources (n = 12)) that were conducted from 2014 up to 2019. After duplication removed, a total of 3150 articles remained (3729 duplicated). Finally, 200 studies were screened for full-text review and, 34 articles with (n = 87,984 patients) were selected for the prevalence and/ or associated factors analysis (Fig. 1).
Characteristics of included studies
Table 1 summarizes the characteristics of the 34 included studies in the systematic review and meta-analysis (10, 11, 19–49). 16 studies were found in Ethiopia(10, 20–34), 8 in Kenya (11, 35–40), 2 in Uganda(48, 49),1 Eritrea(19), 1 in Somali(41),4 Sudan(42–45),2 Tanzania(46, 47).
23 studies were cross-sectional, while the others used either case-control (n = 9) or cohort (n = 2) study design. Most of the studies 23/34(70.5%) were published between 2015 and 2019. The studies included participants, ranging from 40 (45) to 73778(41) (Table 1).
Table 1: Distribution of studies on the prevalence and determinants of pneumonia among under five children in East Africa, 2002–2019
Author/Reference | Year | Country | Study design | Sample size | Prevalence (%) | Quality score |
Shah et al(19) | 2012 | Eritrea | Crossectional | 1502 | 29 | 5/8 |
Negash et al(20) | 2019 | Ethiopia | Cohort | 362 | 21.5 | 9/11 |
Abaye et al(29) | 2019 | Ethiopia | Crossectional | 477 | 18.4 | 6/8 |
Lema et al(30) | 2019 | Ethiopia | Crossectional | 344 | 17.7 | 7/8 |
Fekadu et al(31) | 2014 | Ethiopia | Crossectional | 286 | 16.1 | 7/8 |
Dadi et al(23) | 2014 | Ethiopia | Case control | 356 | | 7/8 |
Geleta et al(21) | 2016 | Ethiopia | case control | 382 | | 8/8 |
Shibre et al(10) | 2015 | Ethiopia | Crossectional | 458 | 5.5 | 6/8 |
Tegenu et al(28) | 2018 | Ethiopia | Crossectional | 306 | 28.1 | 5/8 |
Abuka et al(33) | 2017 | Ethiopia | Crossectional | 206 | 33.5 | 7/8 |
Workineh et al(22) | 2017 | Ethiopia | Case control | 558 | | 7/10 |
Markos et al(25) | 2019 | Ethiopia | Case control | 435 | | 7/10 |
Gedefaw et al(26) | 2015 | Ethiopia | Case control | 244 | | 8/10 |
Tadesse et al(27) | 2015 | Ethiopia | Crossectional | 150 | 26.7 | 8/8 |
Adhanom et al (34) | 2019 | Ethiopia | Crossectional | 252 | 43.7 | 5/8 |
Lenda et al(32) | 2018 | Ethiopia | Crossectional | 458 | 17.6 | 8/8 |
Deribew et al (24) | 2007 | Ethiopia | case control | 168 | 22.6 | 9/10 |
MANYA et al(38) | 2005 | Kenya | case control | 188 | | 7/10 |
Keter et al (50) | 2015 | Kenya | Crossectional | 422 | 67.1 | 6/8 |
Onyango et al(39) | 2012 | Kenya | case control | 206 | | 7/10 |
Muthumbi et al(37) | 2017 | Kenya | Crossectional | 1483 | | 7/8 |
Ndungu et al(35) | 2018 | Kenya | Crossectional | 323 | 74.3 | 6/8 |
Walekhwa et al(40) | 2019 | Kenya | Crossectional | 206 | 20.39 | 7/8 |
Sikolia et al(36) | 2002 | Kenya | Crossectional | 300 | 69.7 | 6/8 |
Ásbjörnsdóttir et al(11) | 2012 | Kenya | Cohort | 365 | 89.8 | 10/11 |
Kinyoki et al(41) | 2017 | Somalia | Crossectional | 73778 | 17 | 6/8 |
Gritly et al (45) | 2018 | Sudan | Crossectional | 40 | 65 | 7/8 |
Salih et al (43) | 2014 | Sudan | Crossectional | 195 | 10.32 | 5/8 |
Gabbad et al (42) | 2014 | Sudan | Crossectional | 282 | 20.2 | 7/8 |
Deng et al (44) | 2019 | Sudan | case control | 108 | | 8/10 |
Ndosa et al (46) | 2015 | Tanzania | Crossectional | 12.3 | | 5/8 |
Lugangira et al (47) | 2017 | Tanzania | Crossectional | 1130 | 22 | 8/8 |
Lindstrand et al (48) | 2018 | Uganda | Crossectional | 1723 | 56 | 6/8 |
Tuhebwe et al (49) | 2014 | Uganda | Crossectional | 278 | 9.4 | 7/8 |
Meta-analysis
Prevalence of pneumonia among fewer than five children in Ethiopia
Most of the studies (n = 23) had reported the prevalence of pneumonia (10, 11, 19, 20, 24, 27–36, 40–43, 45, 47–49). The prevalence of pneumonia were ranged from 5.5% (10) up to 89.8% (11). The random-effects model analysis from those studies revealed that, the pooled prevalence of pneumonia in East Africa was found to be 34% (95%CI; 23.80–44.21; I2 = 99.4%; p < 0.001) (Fig. 2).
Subgroup analysis of the prevalence of pneumonia in Eastern Africa
The subgroup analysis was done through stratified by country, study design, and year of publication. Based on this, the prevalence of pneumonia among under five children was found to be 29 in Eritrea, 22.62 in Ethiopia, 64.3 in Kenya, 29.71 in Sudan, 22 in Tanzania, and 32.72 in Uganda (Supplementary Fig. 1 and Table 2). Based on the study design, the prevalence of pneumonia was found to be 32.33 in cross-sectional studies, 55.68% in cohort studies and 22.6 in case control studies (Supplementary Fig. 2 and Table 2). Based on the year of publication, the prevalence of pneumonia was found to be 33.4 from 2000–2015, while it was 34.29 from studies conducted from 2016–2019(Supplementary Fig. 3, Table 2).
Table 2: Subgroup analysis of the prevalence of pneumonia in Eastern Africa by country, design and year of publication
Variables | Characteristics | Pooled prevalence (95% CI) | I2(P-value) |
By country | Eritrea | 29.00(26.71–31.29) | - |
Ethiopia | 22.62(16.37–28.87) | 96%(< 0.001) |
Kenya | 64.31(42.70-85.92) | 99.1%(< 0.001) |
Sudan | 29.71(11.83–47.60) | 96.1%(< 0.001) |
Tanzania | 22.00(19.58–24.42) | - |
Uganda | 32.72(12.95–78.38) | 99.8%(< 0.001) |
By design | Cross-sectional | 32.33(23.22–41.44) | 99.2% (< 0.001) |
Cohort | 55.68(-11.27-122.60) | 99.8%(< 0.001) |
Case control | 22.60(16.28–28.92) | - |
By year of publication | 2000–2015 | 33.40(11.54–55.25) | 99.6% (< 0.001) |
2016–2019 | 34.29(23.05–44.21) | 99.2%(< 0.001) |
Sensitivity analysis
We employed a leave-one-out sensitivity analysis to identify the potential source of heterogeneity in the analysis of the prevalence of pneumonia in Eastern Africa. The results of this sensitivity analysis showed that our findings were not dependent on a single study. Our pooled estimated prevalence of pneumonia varied between 31.38(22.93–39.83)(11) and 35.3(25.13–45.49)(10) after deletion of a single study(Supplementary Fig. 4).
Publication Bias
We have also checked publication bias and a funnel plot showed symmetrical distribution. Egger’s regression test p-value was 0.63, which indicated the absence of publication bias (Supplementary Fig. 5).
Factors associated with pneumonia
Out of the total included studies 18 studies (10, 20–23, 25–32, 34, 36–39) revealed the factors associated with pneumonia among under five children in Eastern Africa (Table 3)
Table 3: Factors associated with pneumonia in East Africa.
Variables | Odds ratio(95%CI) | Author (reference) | Year | Pooled AOR(95%CI) | I2(P-value) |
Use of wood as fuel source | 1.15(0.47,1.88) | Negash et al (20) | 2019 | 1.53(1.30, 1.77) | 0.0% (0.465) |
2.1 (0.58,6.98) | Lema et al (30) | 2019 |
7.41 (2.75,19.95) | Fekadu et al (31) | 2014 |
1.49 (0.32,6.36) | Shibre et al (10) | 2015 |
3.41(1.5,7.7) | Tegenu et al (28) | 2018 |
2.92 (0.78,10.84) | Abuka et al (33) | 2017 |
1.78(0.28,1.09) | Onyango et al (39) | 2012 |
1.42(0.28,0.92) | Sikolia et al (36) | 2002 |
Cook food in living room | 2.12(0.76, 5.92) | Lema et al (30) | 2019 | 1.47(1.16–1.79) | 0.0% (0.58) |
1.5(1.42, 5.4) | Dadi et al (23) | 2014 |
2.1(1.2, 3.7) | Geleta et al (21) | 2016 |
3.27(1.4,7.9) | Tegenu et al (28) | 2018 |
2.16(1.17,3.99 | Lenda et al (32) | 2018 |
1.35(0.3,0.99) | Sikolia et al (36) | 2002 |
Caring of a child on mother during cooking | 11.76(4.6,30.08) | Lema et al (30) | 2019 | 3.26(1.80–4.72) | 22.5% (0.26) |
5.38(2.13,9.65) | Fekadu et al (31) | 2014 |
1.7(1.317,7.362) | Dadi et al (23) | 2014 |
2.55(1.33,6.5) | Tegenu et al (28) | 2018 |
1.37(0.24,7.83) | Abuka et al (33) | 2017 |
7.37(2.55,21.32) | Tadesse et al (27) | 2015 |
6.2(3.25,11.83) | Lenda et al (32) | 2018 |
Being unvaccinated | 2.6(0.8, 8.1) | Negash et al (20) | 2019 | 2.41(2.00-2.81) | 51.4% (0.055) |
1.6(0.9,2.9) | Geleta et al (21) | 2016 |
4.62(2.64,11) | Tegenu et al (28) | 2018 |
1.68(0.16,2.42) | Abuka et al (33) | 2017 |
2.77(0.19,0.54) | Workineh et al (22) | 2017 |
2.67(0.15,0.92) | MANYA et al (38) | 2005 |
1.68(0.16,2.42) | Onyango et al (39) | 2012 |
Non-exclusive breast feeding | 1.51(0.88,2.58) | Negash et al (20) | 2019 | 2.47(1.79, 3.16) | 65.0% (0.01) |
6(3.33,10.8) | Abaye et al (29) | 2019 |
2.49(0.05,3.7) | Lema et al (30) | 2019 |
2(1.58,7.98) | Dadi et al (23) | 2014 |
3.3(2,5.4) | Geleta et al (21) | 2016 |
2.37(0.16,1.08) | Shibre et al (10) | 2015 |
3.3(1.27,8.3) | Tegenu et al (28) | 2018 |
4.2(1.07,16.6) | Abuka et al (33) | 2017 |
1.64(0.36,0.93) | Workineh et al (22) | 2017 |
6.10(2.5,14.93) | Markos et al (25) | 2019 |
8.33(2.6.3,10.50) | Gedefaw et al (26) | 2015 |
Child history of ARTI | 1.56(0.79,3.06) | Negash AA et al(20) | 2019 | 2.62 (1.68, 3.56) | 11.7% (0.337) |
1.36(0.26,7.21) | Abaye et al (29) | 2019 |
4.26(1.56,11.59) | Lema et al (30) | 2019 |
3.04(1.2,7.77) | Dadi et al (23) | 2014 |
5.2(3.1,8.9) | Geleta et al (21) | 2016 |
4.03(2,8) | Tegenu et al (28) | 2018 |
2.75(1.3,5.81) | Lenda et al (32) | 2018 |
2.71(1.12,6.52) | Onyango et al (39) | 2012 |
17.13(5.01,60.26) | Muthumbi et al (37) | 2017 |
Use of wood as fuel source |
Eight studies found significant association between use of wood as fuel source and pneumonia among under five children. Of these the highest risk factor, AOR = 7.41 (95%CI: 2.75, 19.95), Fekadu et al (31) and lowest risk factor AOR = 1.15(0.47,1.88),Negash et al (20)compared to those who use non wood items as a source of fuel(Table 3). |
Regarding heterogeneity test, galbraith plot showed homogeneity and combining the result of eight studies, the forest plot showed the overall estimate of AOR of using wood as fuel source was 1.53( 95%C I: 1.30, 1.77;I2 = 0.0%;P = 0.465).I-Squared (I2)and P-value also showed homogeneity (Supplementary Fig. 6).Regarding publication bias, a funnel plot showed a symmetrical distribution. During the Egger’s regression test, the p-value was 0.176, which indicated the absence of publication bias (Supplementary Fig. 7). |
We employed a leave-one-out sensitivity analysis to identify the potential source of heterogeneity in the analysis of the pooled estimate of using wood as fuel source as a risk factor of pneumonia in Eastern Africa. The results of this sensitivity analysis showed that our findings were not dependent on a single study. Our pooled estimate of using wood as fuel source varied between 1.409(95%CI, 1.122–1.696) and 1.664(95%CI, 1.321–2.008) after deletion of a single study (Supplementary Fig. 8). |
Cooking food in living room
Six studies found significant association between cooking food at living room and pneumonia among under five children. Of these the highest risk factors, AOR = 3.27(1.4, 7.9)Tegenu et al (28) and lowest risk factor AOR = 1.35(0.3,0.99)Sikolia et al (36) compared to those who cook food at kitchen(Table 3).
Regarding heterogeneity test for cooking food at in living room, galbraith plot showed homogeneity and combining the result of six studies the forest plot showed the overall estimate of AOR of cooking food in living room was 1.47( 95%CI: 1.16–1.79;I2 = 0.0%;P = 0.58).I-Squared (I2)and P-value also showed homogeneity (Supplementary Fig. 9).
Regarding publication of bias for cooking food at home, the funnel plot analysis showed asymmetrical distribution. During the Egger's regression test, the p-value was 0.026, which indicated the presence of publication bias (Supplementary Fig. 10). Trim and fill analysis was done, and 3 study were added and the total number of studies become 9 .The pooled estimate of AOR of preterm becomes 1.406 (Supplementary Fig. 11).
We employed a leave-one-out sensitivity analysis to identify the potential source of heterogeneity in the analysis of the pooled estimate of cooking food in living room as a risk factor of pneumonia in Eastern Africa. The results of this sensitivity analysis showed that our findings were not dependent on a single study. Our pooled estimate of cooking food in living room varied between 1.428(95%CI, 1.102–1.755) and 2.09(95%CI, 1.314–2.875) after deletion of a single study (Supplementary Fig. 12).
Caring of the child on mothers during cooking
Seven studies found significant association between putting a child at the back during cooking and pneumonia among under five children. Of these the highest risk factors, AOR = 11.76(4.6, 30.08) Lema et al (30) and lowest risk factor AOR = 1.37(0.24,7.83) Abuka et al (33) compared to those who didn’t put their baby at their back (Table 3).
Regarding heterogeneity test, galbraith plot showed homogeneity and combining the result of seven studies the forest plot showed the overall estimate of AOR of pneumonia was 3.26( 95%CI: 1.80–4.72;I2 = 22.5%;P = 0.258).I-Squared (I2)and P-value also showed homogeneity(Supplementary Fig. 13).
Regarding test of publication bias a funnel plot showed a symmetrical distribution. Egger’s regression test p-value was 0.074, which indicated the presence of publication bias (Supplementary Fig. 14).
We employed a leave-one-out sensitivity analysis to identify the potential source of heterogeneity in the analysis of the pooled estimate of putting a child at the back during cooking as a risk factor of pneumonia in Eastern Africa. The results of this sensitivity analysis showed that our findings were not dependent on a single study. Our pooled estimate of putting a child at the back during cooking varied between 2.87(95%CI, 1.329–4.426) and 3.59(95%CI, 1.828–5.355) after deletion of a single study(Supplementary Fig. 16).
Being unvaccinated
Seven studies found significant association between being unvaccinated and pneumonia among under five children. Of these the highest risk factors, AOR = 4.62(2.64, 11)Tegenu et al (28) and lowest risk factor AOR = 1.6(0.9,2.9)Geleta et al (21)compared to those who have been vaccinated(Table 3).
Regarding heterogeneity test, galbraith plot showed homogeneity and combining the result of seven studies, the forest plot showed the overall estimate of AOR of not being vaccinated was 2.41( 95%C I: 2.00-2.81;I2 = 51.4%;P = 0.055).I-Squared (I2)and P-value also showed homogeneity (Supplementary Fig. 17).
Regarding publication bias, a funnel plot showed a symmetrical distribution. During the Egger’s regression test, the p-value was 0.177, which indicated the absence of publication bias (Supplementary Fig. 18).
We employed a leave-one-out sensitivity analysis to identify the potential source of heterogeneity in the analysis of the pooled estimate of being unvaccinated as a risk factor of pneumonia in Eastern Africa. The results of this sensitivity analysis showed that our findings were not dependent on a single study. Our pooled estimate of being unvaccinated varied between 2.4(95%CI, 2.07–2.72) and 2.71(95%CI, 2.55–2.86) after deletion of a single study(Supplementary Fig. 19).
Non-exclusive breast feeding
Eleven studies found significant association between non-exclusive breast feeding and pneumonia among under five children. Of these the highest risk factors, AOR = 8.33(2.6.3,10.50) Gedefaw et al (26)and lowest risk factor AOR = 1.51(0.88,2.58) Negash et al (20) compared to those who breast feed exclusively (Table 3).
Regarding heterogeneity test, galbraith plot showed heterogeneity and combining the result of eleven studies, the forest plot showed the overall estimate of AOR of non-exclusive breast feeding was 2.47( 95%C I: 1.79, 3.16;I2 = 65.0%;P = 0.01).I-Squared (I2)and P-value also showed heterogeneity (Supplementary Fig. 20).
Regarding publication bias, a funnel plot showed an asymmetrical distribution. During the Egger’s regression test, the p-value was 0.016, which indicated the presence of publication bias (Supplementary Fig. 21).
Due to presence of publication bias trim and fill analysis was done and 5 studies were added, and the total number of studies becomes 16. The pooled estimate of AOR of non-exclusive breast feeding was found to be 2.05(Supplementary Fig. 22).
We employed a leave-one-out sensitivity analysis to identify the potential source of heterogeneity in the analysis of the pooled estimate of being non-exclusive breast feeding as a risk factor of pneumonia in Eastern Africa. The results of this sensitivity analysis showed that our findings were not dependent on a single study. Our pooled estimate of being for non-exclusive breast feeding is found to be between 1.757(95%CI, 1.49–2.01) and 1.936(95%CI, 1.70–2.17) after deletion of a single study (Supplementary Fig. 23).
History ARTI
9 studies found significant association between history ARTI was considered and pneumonia among under five children. Of these the highest risk factors, AOR = 17.13(5.01,60.26) Muthumbi et al (37)and lowest risk factor AOR = 1.36(0.26,7.21)Abaye et al(29) compared to those who use non wood item as a source of fuel(Table 3).
Regarding heterogeneity test, galbraith plot showed homogeneity and combining the result of nine studies, the forest plot showed the overall estimate of AOR of history ARTI was considered was 2.62( 95%C I: 1.68, 3.56;I2 = 11.7%;P = 0.337).I-Squared (I2)and P-value also showed homogeneity (Supplementary Fig. 24).
Regarding publication bias, a funnel plot showed an asymmetrical distribution. During the Egger’s regression test, the p-value was 0.024, which indicated the presence of publication bias(Supplementary Fig. 25).
Due to presence of publication bias trim and fill analysis was done and 5 studies were added, and the total number of studies becomes 14. The pooled estimate of AOR of history of ARTI was found to be 1.958(Supplementary Fig. 26).
We employed a leave-one-out sensitivity analysis to identify the potential source of heterogeneity in the analysis of the pooled estimate of being history of ARTI as a risk factor of pneumonia in Eastern Africa. The results of this sensitivity analysis showed that our findings were not dependent on a single study. Our pooled estimate of having history of ARTI ranges between 2.195(95%CI, 1.36–3.02) and 3.28(95%CI, 2.153–4.417) after deletion of a single study(Supplementary Fig. 27).
This systematic review and meta-analysis was conducted to assess the magnitude of pneumonia and its associated factors among under-five children in East Africa. Thirty-four studies were included for the final analysis. Twenty-two studies had reported the prevalence of pneumonia and the pooled prevalence of pneumonia in under-five children was found to be 34% with 95% CI of (23.8- 44.21%). This result was higher than a study conducted in Dibrugarh, India which had reported the prevalence of pneumonia in under-five children to be 16.34% (9). This might be due to socioeconomic discrepancies as countries in East Africa are less developed than India. A study conducted in Nigeria had revealed the prevalence of pneumonia in under-five children to be 31.6% which was consistence with the findings of this systematic review (51). This consistency might be due to similarities in socio-economic status as Nigeria is an African country probably having comparable socio-economic status with east African countries.
This systematic review and meta-analysis had also revealed using woods as a source of fuel, cooking foods living rooms, holding children on back while cooking foods, being unvaccinated, history of being not on exclusive breast feeding, history of upper respiratory tract infection and parental smoking as a significant risk factors for increased prevalence of pneumonia among under-five children in East Africa.
Higher odds of pneumonia were observed in under-five children whose family uses wood as a source of fuel. This result was in line with studies conducted in India (52), and Sri Lanka (53); and with systematic reviews conducted in Low and Middle income countries (54), and Africa, China and Latin America (55). It was also consistent with a global review conducted by Jackson et al. (56). The association between using wood as a source of fuel and pneumonia in under-five children might be due to the fact that using woods as a source of fuel results in release of wood smokes containing major air pollutants like carbon monoxide and particulate matters which causes indoor air pollution (57). Indoor air pollution and inhaling wood smoke in turn impairs the function of pulmonary alveolar macrophages and epithelial cells which will increase the likelihood of pulmonary infections including pneumonia (57, 58).
According to this systematic review and meta-analysis, cooking foods in living rooms was found to be significantly associated with occurrence of pneumonia in under-five children as higher odds of pneumonia was exhibited among children living in families who cooks food at living rooms than children living in families who cooks food in kitchen. Holding children on back while cooking foods was another factor found to be significantly associated with pneumonia. This association might be due to the reason that cooking foods in living rooms will cause indoor air pollution and holding a child on back while cooking foods can increase the probability of inhaling smokes and food vapors (steams) which in turn will increase the risk of acquiring pneumonia by altering the structure and function of the respiratory tract (53, 58).
In this systematic review children with history of Upper Respiratory Tract Infections (URTIs) were found to be at increased risk to acquire pneumonia; as the odds of pneumonia among children who had history of URTIs was higher than children without history of URTIs. The reason behind this association might be due to the fact that URTIs will alter the structure and function of the respiratory tract and can cause Lower Respiratory Infections (LRTIs) including pneumonia in two ways— by increasing invasion of the Lower respiratory tract (LRT) with other microorganisms which cause secondary infections or by progressive invasion of LRT with the same microorganism causing the URTIs (Primary infections) (59).
The risk of acquiring pneumonia in unvaccinated children was found to be higher than vaccinated children. This result was similar with studies conducted in Brazil (60), Bellary (7), and India (61). A systematic review conducted by Jackson et al. (56) was also in line with this result. Similarly, children who were not on exclusive breast feeding were at higher risk to develop pneumonia than children who were on exclusive breast feeding for the first 6 months of age. This result was consistent with different studies conducted across the world (7, 56, 62, 63). The reason behind this association might be due to low or weak immunity. Because exclusive breast feeding and vaccination are strategies used to increase the immunity of children and prevent childhood infections. So, children who were not on Exclusive breast feeding and/ or unvaccinated will have weak immunity and increased probability of acquiring infections including pneumonia (64).
Strength and limitations
This study has several strengths: First, we used a pre-specified protocol for search strategy and data abstraction and used internationally accepted tools for a critical appraisal system for quality assessment of individual studies.Second, we employed subgroup and sensitivity analysis based on study country, study design, and publication year to identify the small study effect and the risk of heterogeneity. Nevertheless, this review had some limitations: There may be publication bias because not all grey literature was included and language biases since all included studies are published in English.