Top hospital outpatient diagnoses by ICD-10 code

Millions of people visit hospitals each year without being admitted—but what are they going in for? Using the Atlas All-Payor Claims Dataset, we identified the most common diagnoses seen in outpatient hospital settings, ranked by ICD-10 code based on a percentage of diagnosis volume in hospitals in 2024.

Top 10 outpatient diagnoses in 2024

Fig 1. Analysis of data from the Definitive Healthcare Atlas All Payor Claims product for the calendar year 2024. Claims data is sourced from multiple medical claims clearinghouses in the United States and is updated monthly. Data accessed July 2025.

What were the most common outpatient diagnoses in 2024?

According to our data, the most common hospital outpatient diagnoses in 2024 were essential (primary) hypertension at 3.0%, other long-term (current) drug therapy at 1.4%, and hyperlipidemia, unspecified, at 1.2%.

Essential hypertension (ICD-10 code I10), commonly known as high blood pressure, involves consistently elevated blood pressure levels without a known secondary cause like heart or kidney disease. This condition is a major risk factor for cardiovascular diseases and often requires lifelong management to prevent complications such as heart attack and stroke.

Other long-term (current) drug therapy (ICD-10 code Z79899), the second most common diagnosis, reflects patients undergoing long-term medication therapy for chronic or long-term conditions. This category highlights the crucial role of drug adherence in managing chronic illnesses, ensuring that patients maintain their health and prevent disease progression.

Hyperlipidemia, unspecified (ICD-10 code E785), the third most frequent diagnosis, refers to elevated lipid levels in the blood, which can increase the risk of cardiovascular diseases. Although this condition does not specify a particular type of lipid, it typically involves high levels of cholesterol or triglycerides. Management often includes lifestyle modifications, such as diet and exercise, along with medication.

Overall, the top 10 diagnoses primarily highlight the prevalence of chronic conditions, particularly those related to cardiovascular and metabolic health. Conditions such as hypertension, type 2 diabetes, and heart disease are often interconnected, sharing common risk factors like poor diet, lack of physical activity, and genetic predisposition. This data underscores the critical importance of preventive care and effective management strategies to address these widespread health issues.

What’s behind the growth in outpatient care?

In recent years, a major shift in where patients prefer to receive care has sent waves across the healthcare industry. According to Definitive Healthcare data, and dozens of studies documenting the trend, more procedures and services that have historically been performed in inpatient care settings are now done in outpatient facilities.

Several factors have contributed to the rise in outpatient care. Clinical advancements in minimally invasive surgical procedures and new anesthesia techniques reduce complications and accelerate patient recovery. Meanwhile, the expansion of telehealth technology, remote patient monitoring tools, and EMRs are simplifying the patient monitoring process, lessening the need for admissions. This shift in care is helping to lower overall care costs, improve patient outcomes, and reduce unnecessary admissions.

Learn more

Healthcare Insights are developed with data from the Definitive Healthcare platform. Want even more insights? Start a free trial now and get access to the latest intelligence on hospitals, physicians, and other healthcare providers.