About

NAPPA NAPPA (Nail assessment in psoriasis and psoriatic arthritis) is a modular instrument for the assessment of clinical and patient-reported outcomes in nail psoriasis.

You can also find all this information in our NAPPA Starter-Kit and NAPPA Short Information provided on our Download Section.

NAPPA (Nail assessment in psoriasis and psoriatic arthritis) is a modular instrument for the assessment of clinical and patient-reported outcomes in nail psoriasis.

NAPPA comprises three components: 1. NAPPA-QOL measuring nail-specific quality of life 2. NAPPA-PBI reflecting patient-relevant needs and treatment benefits 3. NAPPA-CLIN recording objective nail status.

The three components (modules) have been developed and validated on an international basis. Thus, several language versions are available. The modules can be used independently from each other.

It has become an international standard to appraise outcomes in medicine based on both objective measurements and subjective evaluation from the patient’s perspective. Most authorities for drug licensing and reimbursement require the proof of clinically relevant incremental benefit when a medical intervention is assessed. For this, many national bodies and reimbursement agencies have defined criteria and – in some cases – thresholds for treatment evaluations which need to be met by scientifically sound and valid methods. For example, the German federal joint committee (GBA) and the German Institute for Quality and Efficiency in Medicine (IQWiG) have defined patient-relevant benefits as major criteria of treatment assessments, including improvements in mortality, morbidity, quality of life, and treatment burden.

According to the German guideline for benefit assessment, the outcomes measurement in skin diseases like psoriasis and nail psoriasis should include two outcomes: First, objective skin condition measured by the dermatologist; second, subjective measurement of disease burden and treatment benefits from the patient perspective. NAPPA has been developed to meet the requirements of national authorities for valid outcomes measurements and to also show maximum feasibility in clinical research and routine use.

The NAPPA development was conducted according to the national and international standards of developing test instruments and outcomes research. All development processes were performed in several countries and languages, thus permitting a cross-cultural adaptive process.

Major steps in the development were a) an international consensus conference on the needs and features of a nail psoriasis outcomes instrument, b) a scientifically stringent study protocol, c) an international item generation from 120 patients with nail psoriasis, d) an expert panel for item selection and discussion, e) a pilot feasibility study on n=55 patients and f) a final validation study in 6 countries / 6 languages on n=203 patients in routine care.

NAPPA-QOL is a 20-item nail specific quality of life questionnaire which assesses specific quality of life conditions in the past week. Answers are given in Likert scales from 0 to 4. Factor analysis revealed three scales named ‘Signs’ (nail status), ‘Stigma’ (nail impact: stigma and emotional status), and ‘Everyday life’ (nail impact: everyday life). For use in clinical trials, a global score including all items without weighting is used and mean values are determined.

NAPPA-PBI is a 24-item questionnaire which assesses patient-defined needs before and patient-rated benefits after treatment. The answers are given in Likert scales from 0 to 4, and a global score is calculated based on the importance-weighted benefit items. The principle of PBI is an advanced mode of goal attainment scaling with standardized goal items.

NAPPA-CLIN has been developed from the NAPSI score, a nail psoriasis-specific score, which in its original version comprises the assessment of matrix and nail bed involvement in every finger and toe by 2 criteria for each nail. The NAPPA-CLIN is a simplified version of the NAPSI which only assesses the least and the worst involved nail of both hands or both feet respectively. Thus, the NAPPA-CLIN scores for hands or feet range from 0 to 16 empirically.

To date, linguistically validated translations of the The NAPPA-PBI and NAPPA-QOL have been performed for:

Czech (Czechia)
Danish (Denmark)
Dutch (Belgium)
English (UK)
English (USA)
French (Belgium)
Greek (Greece)
Italian (Italy)
Japanese (Japan)
Polish (Poland)
Portuguese (Brazil)
Portuguese (Portugal)
Spanish (Spain)

Validation data from the final validation study are available for NAPPA-PBI and NAPPA-QOL in…

German (Germany)
Danish (Denmark)
English (USA)
Italian (Italy)
Japanese (Japan)
Spanish (Spain)

The NAPPA-QOL and NAPPA-PBI questionnaires are filled in by the patient himself. The questionnaire is self-explanatory; yet, patients can be supported if they are not able to fill it in by themselves. In this case, the support needs to be documented.

NAPPA-CLIN is filled by the dermatologist or assisting persons. This part needs a basic understanding of clinical signs at the nails.

The data of NAPPA-QOL and NAPPA-PBI are coded with numbers (0 to 4; “does/did not apply to me” = 5; missing value = -9) and are entered into a spread sheet (e.g. Excel) or statistics program (e.g. SPSS). The spread sheet matrix should be structured as follows: Each row corresponds with one patient and each column corresponds with one variable (=item).

If an item is answered with two or more “x” or by ticking between two checkboxes, it is treated as missing.

The NAPPA-QOL global score is computed by averaging all items. In case more than 25% of the items are missing (5 or more items missing), the score is not computed for the respective patient.

The NAPPA-QOL subscales are computed by averaging the respective items. In case more than 25% of the respective items are missing, the score is not computed for the respective patient.

The weighted NAPPA-PBI global score is computed as follows: Each benefit item is multiplied with the respective importance item, and the product is divided by the sum of all importance items. The results are summed up over all items. The resulting global score ranges from 0 (no benefit) to 4 (highest possible benefit).

For more information, see special manual on Patient Benefit Index (PBI).

See publication of NAPPA validation study (Augustin M et al. Nail Assessment in Psoriasis and Psoriatic Arthritis (NAPPA): development and validation of a tool for assessment of nail psoriasis outcomes. Br J Dermatol 2014; 170 (3): 591-598.)