Between 2000-2014, wireless phone use among foodborne illness cases in Connecticut increased from 3.5% to 26% while landline use decreased from 96.5% to 73.5%. The highest rates of wireless use were among those under 1 year old (30.5%) and the largest increase was among those 50-59 (an 18-fold rise). Wireless uptake grew most rapidly among black (700% increase) and Asian (1000% increase) groups. The change in wireless adoption varied widely by pathogen from a 22% rise for Yersinia cases to a 937% increase for Shiga toxin E. coli cases. Due to declining landline usage especially among youth and minorities, random-digit dialing

1. Paula Clogher, Camille Pottinger, James Meek
Yale Emerging Infections Program
Abstract
Quantifying the Uptake of Wireless Phone Use in Connecticut, 2000-2014; Impact on Random-
Digit-Dial Survey Methodology.
Background: Between 2006 and 2014 the National Center for Health Statistics (NCHS) estimate
of American households with wireless only service increased from 12.8% to 44%. Until the
1990’s, with nearly 90% landline coverage in American households, random-digit-dial (RDD)
phone sampling of households with landline phones was a cost effective and statistically sound
method used by public health researchers to identify control subjects for case-control studies.
With rapid uptake of wireless technology the validity of RDD landline sampling model has been
questioned making it increasingly important to validate the national estimates of wireless phone
use. In Connecticut, FoodNet (CT FN) conducts case-control studies to identify risk factors for
foodborne disease based on statewide population-based surveillance for laboratory confirmed
cases of foodborne pathogens. We describe the uptake of wireless phone use in the cohort of
incident foodborne disease cases identified by CT FN from 2000-2014.
Methods: North American Local Exchange NPA NXX Database, NALENND™, a database that
assigns a line type (e.g., landline, wireless) to phone numbers was purchased and merged with
CT FN data using SAS. Time was aggregated to three five-year increments: 2000-2004, 2005-
2009, 2010-2014. Proportions and rates were calculated to describe the distribution of landline
and wireless phone use among CT FN cases by demographic characteristics and pathogen.
Results: From 2000-2014 wireless phone use increased 6-fold (3.5% to 26%) and landline use
decreased 23.5%. Landline use decreased in all case age groups except for those >50. The
highest rate of wireless use (30.5%) was in the 0-<1 age group and the greatest change in
wireless use, an 18-fold increase, was in the 50-59 age group. The percent change in wireless
line use was greatest among black (700%) and Asian (1000%) groups. The rate of change in
wireless uptake varied widely by pathogen with a low of 22% for cases with Yersinia to a high
937% for cases with Shiga toxin E. coli.
Conclusion: Wireless phone use by CT FN cases increased in all age and racial-ethnic groups
and grew most rapidly among non-white groups. Meanwhile, landline use is decreasing among
children and young adults. High rates of wireless use and decreasing rates of landline use in
pediatric cases most likely represents use patterns of the parent or guardian of the child. Use of
RDD for control recruitment in CT may bias results due to underrepresentation of the young and
minority groups with no landline. Additionally, the observations that the rate of wireless use and
change over time varied dramatically by CT FN pathogen suggests that wireless use may be
linked to behaviors or characteristics specific to exposure which may further contribute to
confounding.