Limits...
A disease-specific measure of health-related quality of life for use in adults with immune thrombocytopenic purpura: its development and validation.

Mathias SD, Bussel JB, George JN, McMillan R, Okano GJ, Nichol JL - Health Qual Life Outcomes (2007)

Bottom Line: Factor analyses were conducted to develop the scale structure and reduce the number of items.Statistically significant differences (p < 0.01) were observed when subjects were categorized by treatment status [S, FT, B, A, PH, and QoL, perceived effectiveness of ITP treatment [S], and time elapsed since ITP diagnosis [PH].Results provide preliminary evidence of the reliability and validity of the ITP-PAQ in adult subjects with ITP.

View Article: PubMed Central - HTML - PubMed

Affiliation: Ovation Research Group, 188 Embarcadero, San Francisco, CA 94105, USA. smathias@ovation.org

ABSTRACT

Background: No validated disease-specific measures are available to assess health-related quality of life (HRQoL) in adult subjects with immune thrombocytopenic purpura (ITP). Therefore, we sought to develop and validate the ITP-Patient Assessment Questionnaire (ITP-PAQ) for adult subjects with ITP.

Methods: Information from literature reviews, focus groups with subjects, and clinicians were used to develop 50 ITP-PAQ items. Factor analyses were conducted to develop the scale structure and reduce the number of items. The final 44-item ITP-PAQ, which includes ten scales [Symptoms (S), Bother-Physical Health (B), Fatigue/Sleep (FT), Activity (A), Fear (FR), Psychological Health (PH), Work (W), Social Activity (SA), Women's Reproductive Health (RH), and Overall (QoL)], was self-administered to adult ITP subjects at baseline and 7-10 days later. Test-retest reliability, internal consistency reliability, construct and known groups validity of the final ITP-PAQ were evaluated.

Results: Seventy-three subjects with ITP completed the questionnaire twice. Test-retest reliability, as measured by the intra-class correlation, ranged from 0.52-0.90. Internal consistency reliability was demonstrated with Cronbach's alpha for all scales above the acceptable level of 0.70 (range: 0.71-0.92), except for RH (0.66). Construct validity, assessed by correlating ITP-PAQ scales with established measures (Short Form-36 v.1, SF-36 and Center for Epidemiologic Studies Depression Scale, CES-D), was demonstrated through moderate correlations between the ITP-PAQ SA and SF-36 Social Function scales (r = 0.67), and between ITP-PAQ PH and SF-36 Mental Health Scales (r = 0.63). Moderate to strong inter-scale correlations were reported between ITP-PAQ scales and the CES-D, except for the RH scale. Known groups validity was evaluated by comparing mean scores for groups that differed clinically. Statistically significant differences (p < 0.01) were observed when subjects were categorized by treatment status [S, FT, B, A, PH, and QoL, perceived effectiveness of ITP treatment [S], and time elapsed since ITP diagnosis [PH].

Conclusion: Results provide preliminary evidence of the reliability and validity of the ITP-PAQ in adult subjects with ITP. Further work should be conducted to assess the responsiveness and to estimate the minimal clinical important difference of the ITP-PAQ to more fully understand the impact of ITP and its treatments on HRQoL.

Show MeSH

Related in: MedlinePlus

Known groups validity: Comparison of scale scores by known groups. *Statistically significant differences between subjects who were currently on treatment and subjects who were not on treatment (p < 0.01). †Statistically significant differences between subjects who indicated that their treatment was extremely to moderately effective and subjects who indicated that their treatment was not effective at all (p < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC1808052&req=5

Figure 1: Known groups validity: Comparison of scale scores by known groups. *Statistically significant differences between subjects who were currently on treatment and subjects who were not on treatment (p < 0.01). †Statistically significant differences between subjects who indicated that their treatment was extremely to moderately effective and subjects who indicated that their treatment was not effective at all (p < 0.05).

Mentions: Subjects were categorized into two groups according to gender, splenectomy status, current ITP treatment status, subject's perception of the effectiveness of ITP treatment, and time elapsed since ITP diagnosis. When subjects were grouped according to gender or splenectomy status, no statistically significant differences were observed for any of the ITP-PAQ scales (data not shown). Subjects who were currently receiving treatment for ITP reported lower scores on all ITP-PAQ scales compared to subjects who were not currently receiving treatment. Statistically significant differences (p < 0.01) were reported for the following ITP-PAQ scales when subjects were categorized by treatment status: Symptoms, Fatigue/Sleep, Bother-Physical Health, Activity, Psychological Health, and Overall QoL (Figure 1). When subjects were categorized by effectiveness of ITP treatment, statistically significant differences (p < 0.05) were observed for the Symptoms and Activity scales (Figure 1), while statistically significant differences were only found for the Psychological Health scale when subjects were categorized according to time elapsed since ITP diagnosis (data not shown). Subjects who had been diagnosed with ITP for < 1 year had a lower mean score on the Psychological Health scale compared to subjects who had been diagnosed with ITP for at least one year (50.38 vs. 66.46, respectively; p = 0.02) (data not shown).


A disease-specific measure of health-related quality of life for use in adults with immune thrombocytopenic purpura: its development and validation.

Mathias SD, Bussel JB, George JN, McMillan R, Okano GJ, Nichol JL - Health Qual Life Outcomes (2007)

Known groups validity: Comparison of scale scores by known groups. *Statistically significant differences between subjects who were currently on treatment and subjects who were not on treatment (p < 0.01). †Statistically significant differences between subjects who indicated that their treatment was extremely to moderately effective and subjects who indicated that their treatment was not effective at all (p < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1808052&req=5

Figure 1: Known groups validity: Comparison of scale scores by known groups. *Statistically significant differences between subjects who were currently on treatment and subjects who were not on treatment (p < 0.01). †Statistically significant differences between subjects who indicated that their treatment was extremely to moderately effective and subjects who indicated that their treatment was not effective at all (p < 0.05).
Mentions: Subjects were categorized into two groups according to gender, splenectomy status, current ITP treatment status, subject's perception of the effectiveness of ITP treatment, and time elapsed since ITP diagnosis. When subjects were grouped according to gender or splenectomy status, no statistically significant differences were observed for any of the ITP-PAQ scales (data not shown). Subjects who were currently receiving treatment for ITP reported lower scores on all ITP-PAQ scales compared to subjects who were not currently receiving treatment. Statistically significant differences (p < 0.01) were reported for the following ITP-PAQ scales when subjects were categorized by treatment status: Symptoms, Fatigue/Sleep, Bother-Physical Health, Activity, Psychological Health, and Overall QoL (Figure 1). When subjects were categorized by effectiveness of ITP treatment, statistically significant differences (p < 0.05) were observed for the Symptoms and Activity scales (Figure 1), while statistically significant differences were only found for the Psychological Health scale when subjects were categorized according to time elapsed since ITP diagnosis (data not shown). Subjects who had been diagnosed with ITP for < 1 year had a lower mean score on the Psychological Health scale compared to subjects who had been diagnosed with ITP for at least one year (50.38 vs. 66.46, respectively; p = 0.02) (data not shown).

Bottom Line: Factor analyses were conducted to develop the scale structure and reduce the number of items.Statistically significant differences (p < 0.01) were observed when subjects were categorized by treatment status [S, FT, B, A, PH, and QoL, perceived effectiveness of ITP treatment [S], and time elapsed since ITP diagnosis [PH].Results provide preliminary evidence of the reliability and validity of the ITP-PAQ in adult subjects with ITP.

View Article: PubMed Central - HTML - PubMed

Affiliation: Ovation Research Group, 188 Embarcadero, San Francisco, CA 94105, USA. smathias@ovation.org

ABSTRACT

Background: No validated disease-specific measures are available to assess health-related quality of life (HRQoL) in adult subjects with immune thrombocytopenic purpura (ITP). Therefore, we sought to develop and validate the ITP-Patient Assessment Questionnaire (ITP-PAQ) for adult subjects with ITP.

Methods: Information from literature reviews, focus groups with subjects, and clinicians were used to develop 50 ITP-PAQ items. Factor analyses were conducted to develop the scale structure and reduce the number of items. The final 44-item ITP-PAQ, which includes ten scales [Symptoms (S), Bother-Physical Health (B), Fatigue/Sleep (FT), Activity (A), Fear (FR), Psychological Health (PH), Work (W), Social Activity (SA), Women's Reproductive Health (RH), and Overall (QoL)], was self-administered to adult ITP subjects at baseline and 7-10 days later. Test-retest reliability, internal consistency reliability, construct and known groups validity of the final ITP-PAQ were evaluated.

Results: Seventy-three subjects with ITP completed the questionnaire twice. Test-retest reliability, as measured by the intra-class correlation, ranged from 0.52-0.90. Internal consistency reliability was demonstrated with Cronbach's alpha for all scales above the acceptable level of 0.70 (range: 0.71-0.92), except for RH (0.66). Construct validity, assessed by correlating ITP-PAQ scales with established measures (Short Form-36 v.1, SF-36 and Center for Epidemiologic Studies Depression Scale, CES-D), was demonstrated through moderate correlations between the ITP-PAQ SA and SF-36 Social Function scales (r = 0.67), and between ITP-PAQ PH and SF-36 Mental Health Scales (r = 0.63). Moderate to strong inter-scale correlations were reported between ITP-PAQ scales and the CES-D, except for the RH scale. Known groups validity was evaluated by comparing mean scores for groups that differed clinically. Statistically significant differences (p < 0.01) were observed when subjects were categorized by treatment status [S, FT, B, A, PH, and QoL, perceived effectiveness of ITP treatment [S], and time elapsed since ITP diagnosis [PH].

Conclusion: Results provide preliminary evidence of the reliability and validity of the ITP-PAQ in adult subjects with ITP. Further work should be conducted to assess the responsiveness and to estimate the minimal clinical important difference of the ITP-PAQ to more fully understand the impact of ITP and its treatments on HRQoL.

Show MeSH
Related in: MedlinePlus