Household telephone survey
The NIS-Teen conducted household interviews between October 6, 2006, and February 7, 2007. Response rates are summarized in . To obtain the sample, 199,897 telephone numbers were called to identify 79,085 households from the infant NIS RDD sample. Of these households, 64,387 (81%) households were screened for adolescents aged 13–17 years at the time of the household interview. Of these households, 6,549 (10%) reported at least one age-eligible adolescent and 5,481 (84%) completed interviews. After removing adolescents ineligible due to their birth date, the final sample of adolescents with completed household interviews was 5,468 adolescents. Of these, 4,356 households completed the health insurance module.
Selected operational results of fourth-quarter 2006 NIS-Teen 2006 and NIS 2006 data collection
Response rates were measured by the methods of the Council of American Survey Research Organizations (CASRO).12
Details of response rates are shown in . For the 2006 NIS-Teen, the CASRO rate was 56% (row 11). The CASRO response rate is the product of the resolution rate (82%, row 5), the screening completion rate (81%, row 7), and the interview completion rate among households with age-eligible adolescents (84%, row 10). The resolution rate is the percentage of the phone numbers released that were determined to be actual telephone numbers; whether they were nonworking, non-residential, or residential numbers. The screening completion rate is the percentage of households in which contacts were made and successfully screened for an age-eligible adolescent. The interview completion rate is the percentage of households with at least one age-eligible adolescent that completed the NIS-Teen household survey.
Response rates for the 2006 NIS for infants were different from rates for the NIS-Teen (). The percentage of households screened for the presence of an age-eligible infant aged 19–35 months was 91% (vs. 81% in the NIS-Teen). The percentage of households with age-eligible infants was 3% (vs. 10% in the NIS-Teen). The CASRO response rate for the 2006 NIS for infants was 62% (vs. 56% in the NIS-Teen). For another comparison, the NHIS data showed that the overall percentage of households with an age-eligible adolescent aged 13–17 years was 14% in 2006. Among households with a landline telephone, 15% had an adolescent; and among households without a telephone, 9% had an adolescent.
Indicators for the PRC phase of the NIS-Teen module are shown in , in rows 13–27. The number of parents or guardians who completed the household survey was 5,468 (row 12); of these 5,468 parents/guardians, 4,192 (77%, row 13) gave consent to contact vaccination providers. Of these, 65% of adolescents had a single identified provider (row 16) and 35% had two or more providers (row 20). Of adolescents with a single provider identified, 96% had a single IHQ mailed to the provider (row 17) and 90% of these adolescents had the provider return the IHQ (row 18). Of adolescents with two or more providers, 87% had an IHQ mailed to all identified providers (row 21) and 77% of these adolescents had all providers return the IHQ (row 22). In summary, of 4,192 adolescents for whom consent was obtained to contact vaccination providers, 3,888 adolescents (93%, row 24) had at least one provider identified and all identified providers were mailed an IHQ. However, of this number, 3,333 adolescents (86%, row 25) had all IHQs returned from the providers. In total, the number of IHQs that were mailed to providers was 5,851 (row 26), with 5,220 (89%, row 27) returned.
Indicators for the provider phase of fourth-quarter 2006 NIS-Teen 2006 and NIS 2006 data collection
Adequate provider data
We received adequate provider data to determine provider-reported vaccination coverage for 53% (n=2,882) of adolescents with completed household interviews. This number was lower than the infant NIS (70%). In our sample, 4,192 households gave consent to contact adolescents' immunization providers. Of households consenting, 3,888 (93%) had IHQs mailed to all providers and, of these, 3,333 (86%) had all IHQs returned. Only 82% contained an immunization history, which was lower than the infant NIS, in which 93% of children with at least one IHQ returned had at least one IHQ containing an immunization history.
Returned immunization histories must have met certain criteria to be considered adequate. If an adolescent had more than one provider return an IHQ, multiple IHQs were merged to create a synthesized provider immunization history consisting of an array of consecutive shot dates and subtypes for each vaccine category. We also created an immunization history from the household-reported information and used a process to compare the household-reported information with the synthesized provider immunization history to determine if it was adequate.
In determining the number of adolescents with adequate provider data, we first identified zero-shot adolescents. These are adolescents who either had (1) no household-reported vaccinations or no vaccination providers identified or (2) no household-reported vaccinations, one or more providers identified, all the identified providers responded, and no provider-reported vaccinations. In our sample, we identified 16 respondents as zero-shot adolescents.
Second, we used criteria to compare the household-reported immunization histories to the synthesized provider immunization histories for each adolescent. If an adolescent had a synthesized provider immunization history in which s/he had completed the 1:3:2:1 vaccine series (≥1 dose of Td or Tdap after age 7 years, ≥3 doses of HepB, ≥2 doses of MMR, and ≥1 dose of VAR), we considered her/him to have adequate provider data, regardless of the household-reported immunization history. Even if s/he had received additional immunizations by the household report that did not appear in the synthesized provider immunization history, these additional immunizations would not change the adolescent's status of having adequate provider data.
Additionally, if the synthesized provider immunization history showed that the adolescent had not completed the 1:3:2:1 vaccine series, we still considered him/her to have adequate provider data as long as the household-reported immunization history did not contain more immunizations than the synthesized provider immunization history. This could occur if (1) an immunization card was used by the household and the number of shots in the synthesized provider immunization history was less than the number of shots reported from the immunization card for any of the following vaccine categories: diphtheria-tetanus-pertussis (DTP), hepatitis B-containing (HEPB), hepatitis A-containing (HEPA), measles-containing (MCV), and varicella-containing (VRC) (213 adolescents met this criteria) or (2) an immunization card was not used by the household, but the household reported that the adolescent had received all recommended vaccines in any of the vaccine categories (DTP, HEPB, HEPA, MCV, and VRC) and the synthesized provider history contained less than two unique shot dates (19 adolescents met this criteria). Subtracting these 232 cases from our sample of 3,098 adolescents with at least one IHQ returned containing an immunization history left 2,866 adolescents with immunization histories and adequate provider data. Adding the 16 zero-shot adolescents to this number gave the final sample of 2,882 adolescents with adequate provider data.