PATIENT BENEFIT INDEX (PBI)
Structure and scope of the Patient Benefit Index
With the Patient Benefit Index an instrument for a validated and standardized measurement of patient defined treatment benefits according to German and international standards exists. The PBI contains two one-sided questionnaires which are to be completed by the patient before and after receiving a treatment. The first one includes a list of 25 treatment goals (Patient Needs Questionnaire: PNQ), a five-step Likert scale (0 = “not important at all” to 4 = “very important”) records how relevant these items are as therapy goals for the individual patient. Alternatively, there is the opportunity to choose the option “does not apply to me”. In the second part of the questionnaire (Patient Benefit Questionnaire: PBQ) the identical items are covered with the question of the extent to which the current therapy has contributed to attaining the therapy goals (scaled from 0 = “treatment did not help at all” to 4 = “treatment helped a lot” and the option “does not apply to me”). The PBI total score is derived from the ratings on both questionnaires and results in a value between 0 (no patient relevant benefit) and 4 (maximum patient relevant benefit). Specifically, each importance rating of a treatment need is divided by the sum of all importance ratings of a patient to obtain relative importance weights. To calculate the PBI, each benefit rating is multiplied by the respective relative importance rating and the products are summed.
Development of the PBI
The PBI for Psoriasis was developed based on a multistage approach:
a) Open patient interviews
100 patients with different skin diseases were writtenly asked about their personal important benefits of the therapy and about their caused by illness impairment.
b) Expert discussion
Out of the results of the open interviews an expert committee of n=6 (dermatologists, psychologists, health economists) and 4 patients created an item pool of 110 items. Each item was evaluated for representability and adequacy for a questionnaire. In the last version of the PBI questionnaire 25 items remained with important and not redundant patient defined treatment goals and benefits.
c) Feasibility testing
The feasibility of the PBI was determined with 50 skin patients. They were asked to fill out the questionnaire and answer further questions about it. More than 95% of the patients stated that the questionnaire is well understandable and easy to fill out as well as contentual regards the benefit concerns of patients.
In two validation studies (together n=1406) reliability and validity of the questionnaire were examined. The PBI proved itself as valid (convergent validity concerning patient satisfaction, treatment efficiency out of physicians’ and patients’ point of view and quality of life) and reliabel (good item selectivity of PNQ, Cronbachs Alpha > 0.91). Over the time of the treatment PBI values increased which shows a high sensitivity. High feasibility was attained by low missing values (under 2% for all items.
Further versions of the PBI
The PBI was translated into different languages in a valid manner (e.g. French, Italian, Spanish, Dutch, Russian). Every valid translation contains the translation of all items, back-translation, comparison of the original version and finally a consensus of all translations in a joint conference with the questionnaire developers and translators.
Numerous disease specific versions were developed, e.g.:
Apart from the treatment goals format and structure of all PBI versions are identical.
Source: Augustin, Radtke, Zschocke, Blome, Behechtnejad, Schäfer, Reusch, Mielke, Rustenbach. The patient benefit index: a novel approach in patient-defined outcomes measurement for skin diseases.
Arch Dermatol Res 2009; DOI 10.1007/s00403-009-0928-8.