Answering your questions: book donations, pipette calibration intervals and comparing two analyzers - Tips From the Clinical Experts - Letter to the Editor

Medical Laboratory Observer, April, 2003 by Daniel M. Baer

Book donations

Q Please give me a list of agencies or lab organizations that accept donations of journals, lies, books and equipment that may be of use to them.

A A number of organizations distribute medical books, journals, supplies and equipment to hospitals and clinics overseas. Each organization has its own requirements for donations it will accept. Some will reimburse the shipping expenses; others will not. You should contact the organization before sending anything.

* Books for Africa

253 E. Fourth St.

St. Paul, MN 55101

Phone: (651) 602-9844

Fax: (651) 602-9848

E-mail: info@booksforafrica.org

www.booksforafrica.org

* Books for Asia

The Asia Foundation

80 Elmira St.

San Francisco, CA 94103

Phone: (415) 982-4640

E-mail: booksforasia@asiafound.org

www.asiafoundation.org/programs/prog-us-bfa.html

* Bridge to Asia

665 Grant Ave.

San Francisco, CA 94108

Phone: (415) 678-2990

E-mail: asianet@bridge.org

www.bridge.org/books.html

The Brother's Brother Foundation

1501 SW Reedsdale St.

Pittsburgh, PA 15233-2341

Phone: (412) 321-3160

Fax: (412) 321-3325

E-mail: niail@brothersbrother.org

www.brothersbrother.org

* Direct Relief International

27 S. La Patera Ln.

Santa Barbara, CA 93117-3251

Phone: (805) 964-4767

Fax: (805) 681-4838

E-mail: info@directrelief.org

www.directrelief.org

* International Book Project

1440 Delaware Ave.

Lexington, KY 40505

Phone: (859) 254-6771;

Toll-free (888) 999-BOOK

Fax: (859) 253-2293

E-mail: books@intlbookproject.org

www.intlbookproject.org

* Sabre Foundation

Scientific Assistance Project

872 Massachusetts Ave., Suite 2-1

Cambridge, MA 02139

Phone: (617) 868-3510

Fax: (617) 868-7916

E-mail: sahre@sabre.org

www.sabre.org

* Sudan American Foundation for Education

4141 N. Henderson Rd., Suite 1205

Arlington, VA 22203

Phone: (703) 525-9045

Fax: (703) 351-0782

E-mail: burchinal@erols.com

www.sudan.com/safe

* Third World Academy of Sciences

POB 586 Enrico Fermi Building

Via Beirut 6

Trieste, Italy

Phone: 39 040 2240327

E-mail: info@twas.org

www.twas.org

--Daniel M. Baer, MD

Professor Emeritus

Department of Pathology

Oregon Health and Science University

Portland, OR

Pipette calibration intervals

Q What time intervals are recommended for calibration/validation of pipettes that are used in a qualitative assay? We currently are doing these quarterly and would like to do them every six months. We need documentation from a reference source to make this change.

A You state that currently you are J calibrating the pipetting devices quarterly and would like to do them every six months as they are used in a qualitative assay. The College of American Pathologists publishes checklists for the Laboratory Accreditation Program. The following information is obtained from the Molecular Pathology checklist, October 2001, pages 61 and 62, pertaining to manual and automated pipettes.

* MOL.39725 - Are non-Class A pipettes (Class A, NIST Standard or equivalent) that are used for quantitative dispensing of materials checked for accuracy and reproducibility at specified intervals and results documented?

* MOL.39750 - Are automatic pipettes checked for accuracy of calibration and reproducibility before being placed in service and at regular intervals thereafter?

Since you are using the pipettes for qualitative assays, it may be acceptable to calibrate such pipettes at six-month intervals. For quantitative assays, the pipette calibration done at quarterly intervals would be recommended.

--Robert M. Nakamura, MD

Chairman Emeritus and Senior Consultant

Department of Pathology

Scripps Clinic

La Jolla, CA

Comparing two analyzers

Q We did a correlation study between two hematology analyzers. One is our main instrument and the other a backup. Are there some more sensitive statistics than just the coefficient of correlation? With all the parameters generated in hematology, it just doesn't seem that I get a feel for how well the instruments correlate.

A The coefficient of correlation is a mathematical representation of the linear best-fit graph of results obtained on two instruments. It tells you the number of units on the "Y" axis for each one unit on the "X" axis. Perfect "correlation" would be 1.000, but there is significant subjective opinion about just what is the tolerable deviation from this perfection.

I referred this question to the general laboratory manager of Alabama Reference Laboratories, Montgomery, AL, who, for 23 years, was the manager of the hematology division. Johnny R. Messick MT (ASCP), SH, offers the following guidelines for establishing correlation between two hematology analyzers used within a single laboratory:

* Establish precision for each. Troubleshoot/fix any imprecision of either instrument prior to further evaluations.

* Perform linear range studies on both. Troubleshoot/fix any deviation of linearity within the medically important range of possible values.

* Remove any bias between the instruments. Bias is defined as "the difference between the true mean and the mean calculated from a series of measurements within a population." In the situation posed by the reader, the backup instrument should correlate with the main hematology analyzer, which we will consider to be the primary or reference method. The results of a different backup instrument can be made to match the results of the main instrument by calibration of the secondary or correlated instrument, using data derived from the primary or reference method.