The World Health Organization (WHO) defines malnutrition as a state of cellular imbalance. Malnutrition adversely affects developing countries and is a risk factor for disease and death in the global population. Protein-energy malnutrition (PEM) is one of the common nutritional deficiencies that generally affects infants and young children between 1 and 5 years, and persists into adulthood due to poor brain and neurological development, a prolonged supply of energy and nutrients increases the probability of infection and even death. Patients with PEM are at higher risk for problems like hypoglycemia, hypothermia, severe infections and electrolyte disturbances, etc. PEM can also lead to preterm birth, infectious diseases and parasitic diseases. Anthropometric measures such as height, body mass, skin fold thickness and arm circumference are considered as important indicators of PEM. In this study, we analyzed the current status of PEM diseases in China in 2019 using data from the Global Burden of Disease Study 2019 (GBD 2019), estimated the incidence trend from 1990-2019 and predicted the future trend of PEM in China from 2020-2029, aiming to provide a reference for the formulation of relevant policies and provide a basis for PEM prevention.
The data of this study were derived from the Global Burden of Disease Study 2019，involving mortality indicators，and incidence indicators in 18 age groups（ranged from 0 to over 85 years grouped by an interval of 5 years） of PEM in China from 1990 to 2019. The age-standardized rates were calculated using
the world standard population. Joinpoint regression analysis was used to calculate the annual percentage change （APC） and annual average percentage change （AAPC） of the incidence rate and 95% confidence interval，and to describe the temporal trend. The autoregressive integrated moving average （ARIMA） model was used to predict the incidence of PEM in China from 2020 to 2029.
In 2019，the standardized incidence ratio（SIR） of PEM in the whole population of China was 1 996.5/100 000，and that in males （2 444.7/100 000） was higher than that in females（1 536.0/100 000）. The SIR of PEM in the whole population in China was lower than that of the world standard population（2 099.4/100 000），and that of PEM in Chinese males was higher than that in the world standard male population（2 304.0/100 000）. The incidence of PEM was highest in <5 years old group （4 402.5/100 000），followed by 80-84 years old group（2 417.7/100 000）. After 5 years old，the incidence of PEM in both males and females increased with age，but that was still higher in males.
The SIR of PEM in China from 1999 to 2019 generally showed six inflection points，which were in 1995，2006，2010，2014，2017 and 2019，respectively. The SIR of PEM in China showed a downward trend in periods from 1990 to 1995（APC=-1.3%） and from 2010 to 2014（APC=-2.3%）（P<0.05）. But from 1995 to 2006 and 2006 to 2010，it showed an upward trend，with APC of 0.9% in 1995，and of 2.5% in 2010，respectively （P<0.05）. The growth trend of the SIR of PEM was the most obvious in 2017-2019，with an APC of 8.9% （P<0.05）. The SIR of PEM in China increased at an average annual rate of 0.7% from 1999 to 2019 （AAPC=0.7%，P<0.05）.
The age-specific incidence of PEM in China from 1999 to 2019 showed that the incidence of PEM decreased at an average annual rate of 2.1% in the population under 5 years old，but showed a steady upward trend in other 17 groups（P<0.05）. In age groups of 75-79 and 80-84，the incidence of PEM increased at each time interval from 1999 to 2019（P<0.05）.（4）The ARIMA model-based prediction showed that the incidence of PEM in China might continue to rise from 2020 to 2029，reaching 7 280.06/100 000 in 2029.