Dr. James Luccarelli, a researcher at Massachusetts General Hospital, recently published a study summarizing the demographic characteristics and medical complications of individuals with PWS who were treated at acute care hospitals in the United States in the 4th quarter of 2019.
This kind of data, gathered from a database called the National Inpatient Sample (NIS) database, provides a snapshot of why individuals with PWS end up in the hospital. The database contains de-identified (e.g., anonymous) information about the hospitalizations with information such as demographics (age, sex, race and ethnicity, etc.), hospital characteristics and discharge diagnoses. Dr. Luccarelli used the medical code specific for PWS - the ICD-10 code Q87.11 - to identify the discharge summaries for patients with PWS, which were then analyzed. It is important to note this ICD-10 code was established on October 1, 2019, after an FPWR-led effort to establish a PWS-specific medical code. ICD-10 codes are used in the medical system to identify the medical diagnoses of the person being treated. The importance of having a PWS-specific code cannot be understated as it makes these kinds of studies, with accurate statistics about medical events in the PWS population, possible.
In total, 540 hospitalizations for individuals with PWS were recorded in U.S. acute care hospitals in the 4th quarter of 2019, occurring almost equally among males and females. The median age at the time of admission was 22 years and ranged from 0-64. Those ranging in age from birth to age 7 accounted for ~26% of the hospitalizations and 25% occurred in those age 37 years or older. Those over the age of 50 accounted for 13.6% of the hospitalizations. Looking at hospitalizations by race, 54.6% of hospitalized individuals with PWS were White, 17.6% were Black, 14.8% Hispanic and 9.3% were individuals of other races. Almost 90% of the hospital admissions were categorized as non-elective, or treatment of an urgent medical issue, and less than 2% of the hospitalizations resulted in death. The median length of hospital stay was 5 days with a median hospital charge of $43,305.
Primary discharge diagnoses in these hospitalizations were most commonly reported as respiratory conditions (20.4%), infectious conditions (13%) and digestive conditions (12%). The incidence of the conditions in those with PWS was compared to those without PWS, and revealed individuals with PWS were significantly more likely to be hospitalized for respiratory failure, septicemia (infection in the blood) or intestinal obstruction or ileus. Mental health diagnoses such as schizophrenia spectrum and other psychotic disorders occurred more frequently in those with PWS than those without. However, depressive conditions commonly reported in non-PWS hospitalizations (4.8%) were not among the principal diagnosis in any individuals with PWS in this sample. In evaluating primary and secondary co-occurring medical problems (comorbidities), sleep apnea was the most commonly diagnosed medical condition (37%) followed by hypothyroidism, hypertension and gastroesophageal reflux (16.7% each). Obesity was included as a diagnosis in 51.8% of those with PWS age 4 and older and was markedly higher than those without PWS. The percentage of those documented as obese increased with age. Coding of a specific body mass were documented in 160 of the 540 individuals with PWS. Of the total sample, 23.1% (n=125 of 540) coded for a BMI >40 (also sometimes called ‘class 3’, 'severe’ or ‘morbid’ obesity) and 14.8% (n=80 of 540) coded for a BMI >50 (‘class 4’ or severe/morbid obesity)
This data makes it clear that chronic medical illness in individuals with PWS is common. Sleep apnea, endocrine disorders, gastrointestinal disorders, infectious diseases, mental health disorders, hypertension, and orthopedic issues ranked among the most commonly coded medical issues in the hospitalizations of those with PWS. The rate of coded obesity in this sample in those over the age of 4 closely matched an FPWR published study of obesity in 165 individuals with PWS, at ~50% obese.
It is important to note that there may be variability in reporting or under-reporting of chronic comorbidities, since some medical providers may not have coded for all chronic comorbidities if the management of these issues was not actively being treated at the time of hospital admission. It is also possible that due to the recency of the ICD-10 code implementation relative to the timing of this sample collection, some individuals with PWS might not have been captured. However, overall, this study has a large sample size and provides insights into medical problems and reasons for hospitalizations in PWS. It also reinforces the importance of having PWS-specific billing codes to collect data that lead to a better understanding of complications associated with PWS in the ‘real world’.
We look forward to comparing this data, which is a snapshot of one point in time, to the PATH for PWS study, a 4-year ‘longitudinal’ natural history study being conducted by the Foundation for Prader-Willi Research, designed to capture the incidence and outcomes of serious medical events occurring in the PWS population. The PATH study began in October 2018 and enrolled over 650 participants with PWS age 5 and older and will conclude in June 2023. We expect the PATH for PWS data will provide an understanding of the serious medical events that occur over time, as well as potential factors that contribute to certain serious medical events. Understanding hospitalization events is critical in understanding the course of the syndrome and the risks contributing to serious medical events in PWS, with the ultimate goal of improving care.