NP Data Set forms and documentation

All available in PDF only

The Researchers Data Dictionary — Neuropathology Data Set (RDD-NP) is intended to be the first and primary resource for researchers analyzing NACC neuropathology data. The NACC Neuropathology Data Set has undergone several revisions since its inception in 2002, the most substantial of which occurred in 2014 with the implementation of version 10 of the Neuropathology Data form. The RDD-NP brings together information from all the original data-collection instruments (Coding Guidebooks and Forms) for all past and current versions of the NP Form.

Our goal in creating the RDD-NP is to provide a comprehensive document describing the data elements available to researchers for analysis of the neuropathology data collected using versions 1, 7, 8, 9, and 10 of the NP Form.

Associated documentation

Neuropathology Data Set, Version 10 (current version, implemented January 2014)

When used alongside the Data Element Dictionary for the version 10 NP Form, this annotated NP Form can provide researchers with an understanding of how the data elements are collected. Be aware, however, that many of these exact variables are not to be found in the The Researchers Data Dictionary — NP Data Set. The annotated NP Form is provided only as an informational tool. For data requests, researchers should always use the variables described in the RDD-NP.

Version 9 (implemented September 2008)

Earlier versions

Selecting variables for data analysis

Several data elements collected in v1-9 of the NP form are not collected in v10, and vice-versa. Version 10 now includes the 2012 NIA-AA criteria for Alzheimer’s disease and the staining methods used, as well as finer detail on vascular, TDP-43, and other pathological features. To clarify the difference between missing data and data not collected due to differences in form versions, codes of -4 = "Not available, NP form version did not collect data this way" were added.

There are also differences in codes for variables that have been continually collected across NP form versions. For example, CERAD neuritic plaque frequency was collected in all versions of the NP form; however, the coding scheme changed in v10: in v1-9, "No neuritic plaques" has a value of 4; in v10, "No neuritic plaques" has a value of 0. In order to provide consistent coding across all versions, derived variables were developed from the original source variables. In analysis files, these derived variables replace the original NP variable. Derived variables are named with the prefix "NACC," while original NP variables begin with the prefix "NP."

When selecting variables for data analysis, be sure to review all data elements in the section of interest. Some variables that differ across forms could not be combined into a single derived variable. For example, the presence of lacunes was slightly different in v9 and v10, so both original source variables are provided. Thus, the investigator will need to decide how to analyze these data keeping in mind the inconsistency.

In addition, original data elements with blank values resulting from skip patterns in v10 of the NP form were recoded to the unknown and missing codes from the gateway question.

Finally, outdated diagnosis variables were removed from this document in order to prioritize newer, more relevant diagnostic criteria and pathologic features; however, all original NP data elements are still available by request.