What is the difference between a Palliative Performance Scale (PPS) score and a Karnofsky Performance Status (KPS) score in assessing a patient's performance status?

From the Guidelines

The Palliative Performance Scale (PPS) and Karnofsky Performance Status (KPS) are distinct tools used to assess a patient's functional status, with the PPS being more suitable for palliative care settings and the KPS for oncology and research settings. The main difference between the two scales lies in their focus and application. The PPS is specifically designed for palliative care settings and measures five parameters: ambulation, activity level, self-care, intake, and level of consciousness, ranging from 0% (death) to 100% (normal function) in 10% increments 1. In contrast, the KPS, developed earlier for oncology patients, primarily focuses on physical ability and medical care requirements, using a scale from 0 (death) to 100 (normal function) in 10-point increments 1.

Some key points to consider when choosing between the PPS and KPS include:

• The PPS provides a more detailed assessment of factors relevant to palliative care, including food/fluid intake and consciousness level 1
• The KPS is more commonly used in oncology and research settings, and is often used in conjunction with other prognostic factors to determine a patient's performance status 1
• The PPS is particularly valuable for prognostication in terminal illness, with scores below 30% often indicating very limited life expectancy 1
• Healthcare providers should select the appropriate scale based on the clinical context, with the PPS preferred in hospice and end-of-life settings, and the KPS in oncology and research settings 1

It's worth noting that the PPS and KPS are not the only tools used to assess a patient's functional status, and other scales, such as the Eastern Cooperative Oncology Group (ECOG) Performance Status scale, may also be used in certain clinical contexts 1. However, the PPS and KPS are two of the most widely used and well-established scales, and are often used in conjunction with other prognostic factors to determine a patient's overall performance status and inform treatment decisions 1.

From the Research

Overview of PPS and KPS Scores

• The Palliative Performance Scale (PPS) score and the Karnofsky Performance Status (KPS) score are two tools used to assess a patient's performance status.
• Both scores are used to evaluate the functional status of patients, particularly those with cancer or other life-limiting illnesses.

Key Differences Between PPS and KPS Scores

• The KPS score is an 11-point scale, with higher scores indicating better functional status 2.
• The PPS score is also a scale used to assess functional status, but its specific points and scoring system differ from the KPS 3.
• The KPS score has been widely used for over 60 years and has undergone several adjustments since its initial development 4.

Interchangeability of PPS and KPS Scores

• Studies have shown that the PPS and KPS scores are interchangeable in certain contexts, such as in prognostic tools 3.
• A direct positive linear relationship has been found between the KPS and PPS scores, suggesting that they can be used interchangeably as functional tools 3.
• However, the interchangeability of the PPS and KPS scores may be population-specific, and caution should be exercised when using them in different patient populations 3.

Predictive Validity of PPS and KPS Scores

• Both the PPS and KPS scores have been shown to have predictive validity in terms of patient survival 5, 2, 6.
• The KPS score has been found to be a significant predictor of graft and patient survival after liver transplantation 6.
• The PPS score has also been used as a prognostic tool in palliative care, and its interchangeability with the KPS score has been established in certain contexts 3.