PRO instrument and its types

Patient-Reported Outcomes (PROs) is “ a unique health status indicator that reveals the current and past scenarios of a ones health condition by the patient them self, without any other interpretation (clinician or care giver). “Patient-Reported Outcome” (PRO) is considered a broad phenomenon, encompassing various factors of perceiving and quantifying a person’s health status, which includes health conditions (physical and mental), health related quality of life (HRQOL), social well being, clinical trials, functional status linked with the treatment taken by the patient etc. This self- appraisal system is high essential to identify the best practices of a health care that is qualified to be a good outcome leading to a patient centered health care system

A PRO instrument is a rating scale that critically evaluates the health outcomes, satisfaction scores etc in a patients viewpoint. PRO instruments are considered as a primordial quality indicator for health care service, which gives valuable insights to the policy makers, demand market and clinical researchers. Literature has identified several crucial factors for development of a PRO instrument namely 

1. Study parameters should hold strong literature support
2. Should possess a conceptual structure
3. Should be drafted based on a end-point model
4. Study must possess ideal number of study items
5. The model should conceal identity of the patients
6. Reproducible at any given point of time
7. The questionnaire should be simplified and understandable to the patients

Information’s retrieved by the PRO instruments are instrumental in enhancing the relationship between the patient, his/her family and the doctors on the whole. Further, the universal availability of the content is expected to bring upon striking changes in the policies by the regulatory authorities, drug developers, researchers, technologists and be used for advanced clinical trials over the time. 

PRO instruments and its types

Any PRO instrument is developed adopting four essential steps as approved by US-FDA. This includes the a. Hypothesis derivation and drafting of the framework         b. Identifying the literature gaps and deleting or adding the components based on it    c. critical content validation of the instrument; defining of the scoring indices and       d. Final draft of the SOP, evaluation of the patient response in different perspectives, need for translation, changes for different geographical locations will be executed. 

Generally PRO instruments are developed based on the need, intended purpose and the target population. The commonly known types of PRO instruments are

• Generic
• Disease specific
• Population specific
• Dimension specific
• Individualized
• Summary items
• Utility measures

Generic PRO instrument

Generic PRO instruments are used to measure broad health aspects, illness outcomes and are applicable for a wide spectrum of patient groups and population across the countries. The key benefits of generic PRO instrument is that they are ideally suitable to evaluate large number of health disorders and can be used for comparative studies among different patient groups, treatment methods to determine the competency of the models. Additionally, generic PRO instrument finds its applications in normative studies on large population to assess the health system, health interventions, to understand the co-morbidities and to study the effect of latest health care methodologies, clinical trials etc. However, this instrument is less sensitive as compared to other models. Classic examples may include SF-36, which studies the physical and mental component of health in an 8-dimensional scoring matrix, Psychological General Well-Being Index (PGWBI)

Disease specific

This instrument aims to estimate the patient’s view of a specific disease or disorder Specific instruments are made developed targeting specific health ailments. For example: Rheumatoid Arthritis Quality of Life questionnaire (RAQoL) developed to evaluate the patient purview of health care and quality of life with Rheumatoid Arthritis, The Asthma Quality of Life Questionnaire contains 32 items yielding four dimension scores from factors namely symptoms, activity limitations, emotional function, and environmental vulnerability.

Population specific

Population-specific instrument are developed targeting a specific demographic group (children or elderly people) and geographic groups. The term “Population specific” can be classified based on disease condition, treatment methods, population and geography. The population specific PRO is a sensitive tool is developed in precise manner to obtain information’s in a narrowed window.  Example: The Child Health and Illness Profile/CHIP developed for adolescents; Cambridge Pulmonary Hypertension Outcome Review (CAMPHOR)

Dimension specific

Dimension-specific instrument evaluates a particular aspect of a person’s health. The classic examples are physical function, psychological wellness, personal strengths, global health perspectives, specific role based perceptions (house hold works, job, finance), personal put up (appearance, spiritual viewpoint, gratification). This instrument is resourceful in providing specific information as compared to the generic or population specific PRO instruments and they are highly competent. It provides wide range of reliable data for a better interpretation. The Beck Depression Inventory contains 21 items that effectively address symptoms of depression[4]

Individualized PRO instrument

Individualized instruments enable patients to frame their own choice of items and can evaluate the significance of individual items such as the health issue, other concerns or factors that are not predetermined by the evaluator. It basically responds to the concerns of the individual patient and not based on any health standard. Therefore individualized instruments are known to have higher content validity. Classic example of this PRO instrument is: The Patient Generated Index where the respondents are asked to list the five most important areas of their lives; Schedule for the Evaluation of Individual Quality of Life (SEIQoL)

Summary Items

Summary item is a versatile PRO instrument where respondents are asked to consolidate the varied aspect of health condition via a single item or a very small number of items. It is less time consuming and is used to get inputs from large sample groups of a general population leading to ample correlative evidences[5]. However, summary item restricts the specific inferences that can be made on a specific health disorder, which is due to its conciseness. Example: Questions (regarding limiting enduring illness) in General Household Survey; the General Household Survey for England and Wales on chronic illness and disability.

Utility measures

Utility measures, involves choice or values pertaining to an individual health condition and represents it as a single index/score. This PRO instrument evaluates the overall strength of health status in a society and is used for cost-utility analysis. It is considered a generic type PRO however uses specific numerical evaluation methods to study health in a broad spectrum. It is used to compare treatment methods of different health problems and its economic evaluation. Utility measures are brief models and not applicable for large number of states. Example: The EuroQol EQ-5D contains five items namely mobility, self-care, main activity, pain/discomfort and anxiety/depression; Utility measure for major, unipolar depression (McSad)

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