Systematic review of diarrhea duration and severity in children and adults in low- and middle-income countries

Abstract

Background: Diarrhea is a leading cause of morbidity and mortality globally; yet the overall burden of diarrhea in terms of duration and severity has not been quantified. As improvements in treatment lead to decreases in diarrhea mortality, it is important to understand the substantial impact of diarrhea morbidity on disability among children and adults worldwide.

Methods: We conducted a systematic review to generate estimates of duration and severity outcomes for individuals 0-59 mos, 5-15 yrs, and ≥ 16 yrs, and for 3 severity indexes: mild, moderate, and severe.

Results: We estimate that among children under-five, 64.8% of diarrheal episodes are mild, 34.7% are moderate, and 0.5% are severe. On average, mild episodes last 4.3 days, and severe episodes last 8.4 days and cause dehydration in 84.6% of cases. We estimate that among older children and adults, 95% of episodes are mild; 4.95% are moderate; and 0.05% are severe. Among individuals ≥ 16 yrs, severe episodes typically last 2.6 days and cause dehydration in 92.8% of cases.

Conclusions: Moderate and severe episodes constitute a substantial portion of the total envelope of diarrhea among children under-five (35.2%; about 588 million episodes). Among older children and adults, moderate and severe episodes account for a much smaller proportion of the total envelope of diarrhea (5%), but the absolute number of such episodes is noteworthy (about 21.5 million episodes among individuals ≥ 16 yrs). Hence, the global burden of diarrhea consists of significant morbidity, extending beyond episodes progressing to death.

Figure 1

Flow chart diagram of the systematic review process. ¹Main reasons for exclusion: report of one etiologic agent (n = 30); inadequate definition of diarrhea (n = 15); overlapping age categories (n = 17); no outcome of interest (n = 12); diarrhea recall beyond 2 weeks (n = 11); unclear/problematic methodology (n = 11); data in unusable form (n = 6); full episodes not followed (n = 6); not representative of general population (n = 4); combined data on hospital inpatients & outpatients (n = 7). ²Main reasons for exclusion: report of one etiologic agent (n = 20); overlapping age categories (n = 12); not representative of general population (n = 5); report of nosocomial infection (n = 3); unclear/problematic methodology (n = 3); diarrhea recall beyond 2 weeks (n = 4); inadequate definition of diarrhea (n = 1); no outcome of interest (n = 1); combined data on hospital inpatients & outpatients (n = 1). ³All studies reported data on children 0-59 mos of age; one study reported data on children 5-15 yrs of age. ⁴Study design: cohort (n = 27); RCT (n = 10); case-control (n = 4). Study location: community-based (n = 34); hospital-based (n = 7). ⁵All studies reported data on children 0-59 mos of age, only. ⁶Study design: cohort (n = 15); RCT (n = 5); case-control (n = 7). Study location: community-based (n = 10); hospital-based (n = 17). ⁷Study design: cohort (n = 2); RCT (n = 2). Study location: community-based (n = 2); hospital-based (n = 2). ⁸Study design: cohort (n = 4); RCT (n = 2). Study location: community-based (n = 2); hospital-based (n = 4).

Figure 2

Location of studies reporting diarrhea duration and severity outcomes for children and adults. Locations of 61 unique studies; one study represented at 3 different locations.

Figure 3

Model of the duration and severity of diarrhea among children 0-59 mos of age.

Figure 4

Model of the duration and severity of diarrhea among individuals ≥ 16 yrs of age.