Wayne J. Morgan, Donald R. VanDevanter, David J. Pasta, Aimee J. Foreman, Jeffrey S. Wagener, Michael W. Konstan, Wayne Morgan, Michael Konstan, Ted Liou, Susanna McColley, Ann McMullen, Alexandra Quittner, Warren Regelmann, Clement Ren, Margaret Rosenfeld, Greg Sawicki, Michael Schechter, Donald VanDevanter, Jeffrey Wagener, Marlyn Woo, Dana Brasfield, Raymond Lyrene, Lawrence Sindel, Dion Roberts, John Carroll, Robert Warren, Louay Nassri, Paula Anderson, Mark Brown, Amy Silverthorn, Peggy Radford, Gerald Gong, Gregory Legris, Gerald Greene, Reddivalam Sudhakar, Arnold Platzker, Bruce Nickerson, Karen Hardy, Ivan Harwood, Gregory Shay, Bryon Quick, Allan Lieberthal, Richard Moss, Chris Landon, Yvonne Fanous, Jay Lieberman, Eugene Spiritus, Bradley Chipps, Ruth McDonald, Mark Pian, Gerd Cropp, Nancy Lewis, Dennis Nielson, Bertrand Shapiro, Jeff Wagener, Frank Accurso, Milene Saavedra, Karen Daigle, Jacob Hen, Regina Palazzo, Kathryn Dodds, Raj Pad-man, John Goodill, Glenna Winnie, Lea Davies, Tony Kriseman, Jorge Sallent, Joseph Chiaro, Martin Kubiet, Sue Goldfinger, Morton Schwartzman, Carlosenrique Diaz, Kevin Maupin, Eduardo Riff, David Geller, Floyd Livingston, Kunjana Mavunda, Jose Birriel, Luis Faverio, David Rosenberg, David Schaeffer, James Sherman, Mary Wagner, Michael Light, Bruce Schnapf, Gary Montgomery, Kevin Kirchner, Mark Weatherly, Daniel Caplan, Margaret Guill, Valera Hudson, Javeed Akhter, Donald Davison, Steven Boas, Susanna McColley, Youngran Chung, Rennee Latner, Gabriel Aljadeff, Youngran Chan, Jerome Kraut, Arvey Stone, John Lloyd Still, Girish Sharma, Lanie Eagleton, Patricia Hopkins, Umesh Chatrath, Lucille Lester, Young-Jee Kim, Veena Anthony, Howard Eigan, Michelle Howenstine, Pushpom James, Edward Gergesha, James Harris, Robert Plant, Veljko Zivkovich, Angela Collins, Edward Nassif, Richard Ahrens, Daniel Doornbos, Joseph Kanarek, Richard Leff, Pamela Shaw, Elanor Demoss, Maria Riva, Leonard Sullivan, Michael Anstead, Jamshed Kanga, Nemr Eid, Ron Morton, Bettina Hilman, Kim Jones, Scott Davis, Ralph Harder, Tom Lever, Anne Marie Cairns, Edgar Caldwell, Jonathan Zuckerman, Peter Mogayzel, Beryl Rosenstein, John McQuestion, Donna Perry, Samuel Rosenberg, Robert Gerstle, Andrew Colin, Mary Ellen Wohl, Allan Lapey, William Yee, Brian O'Sullivan, Robert Zwerdling, Ibrahim Abdulhamid, Adrian O'Hagan, John Schuen, Lawrence Kurlandsky, Richard Honicky, Douglas Homnick, John Marks, Bohdan Pichurko, Norma Maxvold, Samya Nasr, Richard Simon, Wan Tsai, Dana Kissner, John McNamara, Nancy Henry, Stephen Marker, Michael Pryor, Warren Regelmann, Lynn Walker, Jim Woodward, Louis Mizell, Suzanne Miller, Daniel Rosenbluth, Philip Black, Michael McCubbin, Alan Cohen, Thomas Ferkol, George Mallory, Anthony Rejent, Bruce Rubin, Gavin Graff, Peter Konig, John Colombo, Peter Murphy, William Boyle, Worth Parker, Chandler Patton, Robert Zanni, Arthur Atlas, Nelson Turcios, Lourdes Laraya-Cuasay, Dorothy Bisberg, Helen Aguila, Sarah Allen, David James, Elizabeth Perkett, Marsha Thompson, Sonia Budhecha, Ruben Diaz, Jonathan Rosen, Robert Kaslovsky, Ronald Percciacante, Drucy Borowitz, Joseph Cronin, Colin McMahon, Lynne Quittell, Robert Giusti, Rubin Cohen, Joan DeCelie-Germana, Jack Gorvoy, Kalpan Patel, Meyer Kattan, Allen Dozor, Emily DiMango, Maria Berdella, Ran Anbar, Debra Ianuzzi, James Sexton, Catherine Tayag-Kier, John McBride, Clement Ren, Karen Voter, Mary Dimaio, John Georgitis, Joseph Marc Majure, Maria Martinez, Clarke McIntosh, Margaret Leigh, Michael Schechter, Hugh Black, James Hughes, Anand Kantak, Robert Wilmott, Gregory Omlor, Robert Stone, Karen McCoy, James Acton, Carl Doershuk, Michael Konstan, Robert Fink, Michael Steffan, Pierre Vauthy, Patricia Joseph, Santiago Reyes, John Kramer, James Royall, Jay Eisenberg, Michael Wall, Stanley Fiel, Thomas Scanlin, Shroti Phadke, Glenna Winnie, Joel Weinberg, William Sexauer, Stephen Wolf, Douglas Holsclaw, Debra Klein, Stuart Warren, Robert Kinsey, Carlos Perez, Muttiah Ganeshanathan, James Shinnick, Howard Panitch, Laurie Varlotta, Cynthia Robinson, Jose Rodriguez Santana, Mary Ann Passero, Jane Gwinn, Robert Baker, Michael Bowman, Patrick Flume, Daniel Brown, Roxanne Marville, James Wallace, Rodney Parry, Don Ellenburg, John Rogers, Ricky Mohon, Joel Ledbetter, Aram Hanissian, Robert Schoumacher, Preston Campbell, Christopher Harris, Bonnie Slovis, Dennis Stokes, Kathryn Hale, Marcia Katz, Dan Seilheimer, Marianne Sockrider, Allan Frank, James Daniel, James Cunningham, Iley Browning, John Bray, Amanda Dove, Fernando Mandujano, Larry Tremper, Martha Morse, Donna Willey-Courand, Steven Copenhaver, John Pohl, Bennie McWilliams, Marie Martine-Logvinoff, Marsh Wallace, Robert Klein, Rodolfo Amaro, Leslie Couch, Michael Brown, Claude Prestidge, Stephen Inscore, Andrew Lipton, Barbara Chatfield, Theodore Liou, Bruce Marshall, Thomas Lahiri, Donald Swartz, Laurie Whittaker, Karl Karlson, Ignacio Ropoll, Thomas Rubio, Joel Schmidt, David Thomas, John Osborn, Deborah Froh, Benjamin Gaston, Greg Elliott, Ronald Gibson, Bonnie Ramsey, Michael McCarthy, Lawrence Larson, David Ricker, Mark Robbins, Moira Aitken, Julia Emerson, Stephen Aronoff, Kathryn Moffett, Julie Biller, Mark Splaingard, Bradley Sullivan, Paul Pritchard, Stu Adair, Peter Holzwarth, Guillermo Dopico, Keith Meyer, Christopher Green, Michael Rock

To evaluate several alternative measures of forced expiratory volume in 1 second percent predicted (FEV1 %pred) variability as potential predictors of future FEV1 %pred decline in patients with cystic fibrosis. We included 13 827 patients age ≥6 years from the Epidemiologic Study of Cystic Fibrosis 1994-2002 with ≥4 FEV1 %pred measurements spanning ≥366 days in both a 2-year baseline period and a 2-year follow-up period. We predicted change from best baseline FEV1 %pred to best follow-up FEV1 %pred and change from baseline to best in the second follow-up year by using multivariable regression stratified by 4 lung-disease stages. We assessed 5 measures of variability (some as deviations from the best and some as deviations from the trend line) both alone and after controlling for demographic and clinical factors and for the slope and level of FEV1 %pred. All 5 measures of FEV1 %pred variability were predictive, but the strongest predictor was median deviation from the best FEV1 %pred in the baseline period. The contribution to explanatory power (R(2)) was substantial and exceeded the total contribution of all other factors excluding the FEV1 %pred rate of decline. Adding the other variability measures provided minimal additional value. Median deviation from the best FEV1 %pred is a simple metric that markedly improves prediction of FEV1 %pred decline even after the inclusion of demographic and clinical characteristics and the FEV1 %pred rate of decline. The routine calculation of this variability measure could allow clinicians to better identify patients at risk and therefore in need of increased intervention.