PASS Overview and Instructions

The Progressive Aphasia Severity Scale (PASS) is a scale used to rate change from the patient’s premorbid baseline across domains of speech, language, and functional and social communication skills (see table below). Ratings are made from “normal” (0), to “questionable/very mild” (0.5), “mild” (1.0), “moderate” (2.0), or “severe” (3.0) impairment. These ratings are meant to reflect the clinician’s best judgment of the overall level of impairment in each domain based on history of problems in daily life and deficits on examination.

Ratings are made by a clinician after a structured clinical assessment, including interviews separately with the patient and informant, and an examination of the patient. The informant should be someone who knows the patient well, usually a spouse, adult child, or sibling.

PASS Domains / Description
Articulation / ability to say sounds and syllables accurately and effortlessly
Fluency / degree to which speech flows easily or is interrupted by hesitations, fillers, pauses; reduced fluency is associated with decreased phrase length and words per minute
Syntax and Grammar / use of word forms (run, ran), functor words (the, an), and word order when forming phrases and sentences in primary modality (speech or writing)
Word Retrieval and Expression / ability to express the intended word through primary modality (speech or writing)
Repetition / ability to repeat words, phrases, sentences; difficulty should not be attributable to working memory problem; do not penalize for sound distortions resulting from apraxia of speech or dysarthria
Auditory Comprehension / ability to understand spoken phrases and sentences (e.g., conversation, commands)
Single Word Comprehension / ability to understand spoken or written single words
Reading / ability to decode and understand written material; difficulty should not be attributable to an elementary visual problem
Writing / ability to write and spell; difficulty should not be attributable to an elementary motor problem
Functional Communication / ability to communicate despite the speech/language impairment; ability to compensate for the impairment
PASS Supplemental Domains / Description
Initiation of Communication / tendency to take an active or passive role in communication exchanges
Turn Taking / ability to take turns during conversation versus speaking/writing over another person
Generation of Language / ability to use novel language to express oneself versus using stereotyped or scripted language

A.  Informant Assessment:

1)  Questionnaire (attached)

The PASS questionnaire is to be completed by the informant at the initial and follow-up clinical encounters. It is organized according to the PASS domains with the exception of repetition, which is excluded from the questionnaire as it is not a readily observable skill in daily life. Each section begins with a general question about changes in functioning, and the section can be skipped if there are no reported changes. Subsequent questions ask about the frequency, severity, and characteristics of the problem. The response format is multiple choice, and each section has space for the informant to write in comments and examples.

Ideally, the questionnaire is completed before the appointment. In our practice, when the patient is known to us as a progressive aphasia patient (either by previous evaluation or by review of outside medical record), we mail the questionnaire to the informant before the appointment and ask him/her to bring the completed questionnaire. In a busy practice when it is not always possible to mail the questionnaire ahead of time, another option is to ask the informant to complete the questionnaire in the waiting room.

The completed questionnaire can then be used to guide the interview. When the questionnaire cannot be completed ahead of time, the clinician and informant can go through the questions together during the interview.

2)  Interview

The informant interview is an opportunity for the clinician to probe areas of reported change in the patient’s functioning. If the questionnaire has been completed, the clinician can review the responses and probe areas that are unclear or require further explanation. If the questionnaire has not been completed, the clinician can use the questionnaire to perform a structured interview of the informant. The clinician should ask any further questions needed to judge the patient’s daily functioning, being sure to note any additional information.

B.  Patient Assessment:

1)  Interview

When possible, the patient assessment should begin with an interview to learn the patient’s perspective on his/her own daily functioning. This is particularly informative in situations when the informant had not been aware of a problem or its frequency/severity, and only the patient is able to describe it accurately (especially for patients with milder impairment).

The PASS informant questionnaire can be used to structure the interview with the patient.

2)  Testing (materials attached)

The speech/language testing can be done using items from the clinician’s existing arsenal of tests, so long as the PASS domains are adequately assessed. Attached are the tasks that we use; these can provide a model for what is needed to rate the PASS. Different stimuli can be substituted according to the clinician’s preferred tools.

C.  PASS Ratings:

Having gathered information from the informant (questionnaire and interview) and patient (interview and testing), the clinician then makes a clinical judgment about the presence and severity of impairment in each of the PASS domains. The PASS worksheet provides brief descriptions of each rating to help the clinician determine which one best matches the patient’s situation.

In situations when it is difficult to decide between two ratings, it may be helpful to go back to the patient or informant and try to obtain further examples or clarification. When this is not possible, we recommend giving the patient “the benefit of the doubt” and assigning the more mild rating.

D.  Reliability and Validity of these measures:

Our standard protocol dictates that ratings are first made independently by each clinician (blind to each others’ ratings), thus enabling inter-rater reliability analysis. Once all data are collected and scored, a consensus discussion is employed to adjudicate differences. Interrater reliability of the two clinicians’ independent PASS measures was assessed using intraclass correlation (ICC). Inter-rater reliability (between neurologist and speech pathologist) of PASS ratings was high for three domains initially analyzed. Further inter-rater reliability analyses are in progress.

We investigated the relationships between performance-based language measures and the individual PASS domain ratings to assess validity. The degree of impairment reflected by PASS scores was closely related to specific performance deficits, supporting the validity of the scale.

E.  Training of new raters:

We are developing case study modules to be used in the training of new raters. Modules consist of the history, informant questionnaire responses and any additional information obtained during the interview, and information from the patient examination, including the interview, audio speech samples, and test performance results. We will provide descriptions of our process in selecting ratings, including examples of how to resolve disagreements between raters.

9/13/12