A prerequisite for need to exist is that an individual has the ability to benefit from receipt of a health care service at the individual level.
Judged subjectively this is often called wants, to distinguish it from an objective judgment about appropriate treatment.
These are distinguished from what is actually purchased, which is demand.
For societal level judgments, other factors such as resource constraints and cultural norms may influence judgments of what constitutes health care need, especially what needs can be met from the public purse.
World Health Organization. European Observatory on Health Systems and Policies. Glossary. 2009.