Not all preventive care services save money and some actually increase healthcare costs, according to a new study.

Preventive care services should be evaluated for cost effectiveness on an individual basis, according to a study from the National Coalition on Health Care. The cost impact of vaccines, health screenings and lifestyle changes depends on a variety of factors. These include the type of intervention, a target population’s risk for developing a disease, and how often the service is provided.

Cost savings for preventive care services are hard to calculate because most introduce additional medical costs from screenings, doctor visits, and drug costs, according to study author Louise B. Russell. Increasingly, the U.S. healthcare system is focused on prevention as a way to reduce costs associated with chronic diseases such as diabetes and hypertension.