A new measure of patient satisfaction with ocular hypotensive medications: the Treatment Satisfaction Survey for Intraocular Pressure (TSS-IOP).
OBJECTIVE
To validate the treatment-specific Treatment Satisfaction Survey for Intraocular Pressure (TSS-IOP).


METHODS
Item content was developed by 4 heterogeneous patient focus groups (n = 32). Instrument validation involved 250 patients on ocular hypotensive medications recruited from ophthalmology practices in the Southern USA. Participants responded to demographic and test questions during a clinic visit. Standard psychometric analyses were performed on the resulting data.


METHODS
Of the 412 patients screened, 253 consented to participate, and 250 provided complete datasets. The sample included 44% male (n = 109), 44% Black (n = 109) and 57% brown eyed (n = 142) participants, with a mean age of 64.6 years (SD 13.1) and a history of elevated IOP for an average of 8.4 yrs (SD 7.8). A majority was receiving monotherapy (60%, n = 151).


RESULTS
A PC Factor analysis (w/ varimax rotation) of the 31 items yielded 5 factors (Eigenvalues > 1.0) explaining 70% of the total variance. Weaker and conceptually redundant items were removed and the remaining 15 items reanalyzed. The satisfaction factors were; Eye Irritation (EI; 4 items), Convenience of Use (CofU; 3 items), Ease of Use (EofU; 3 items), Hyperemia (HYP; 3 items), and Medication Effectiveness (EFF; 2 items). Chronbach's Alphas ranged from.80 to.86. Greater distributional skew was found for less common experiences (i.e., HYP & EI with 65% & 48.4% ceilings) than for more common experiences (i.e., EofU, CofU, EFF with 10.8%, 20.8% & 15.9% ceilings). TSS-IOP scales converged with conceptually related scales on a previously validated measure of treatment satisfaction, the TSQM (r =.36 to.77). Evidence of concurrent criterion-related validity was found. Patients' symptomatic ratings of eye irritation, hyperemia and difficulties using the medication correlated with satisfaction on these dimensions (r =.30-.56, all p <.001). Clinicians' ratings of IOP control, severity of side effects and problematic medication use correlated with patients' satisfaction scores on these dimensions (r =.13-.26, all p <.01).


CONCLUSIONS
This study provides initial evidence that the TSS-IOP is a reliable and valid measure, assessing patients' satisfaction with ocular hypotensive medications.
Atkinson
Mark J
MJ
Worldwide Outcomes Research, Pfizer, La Jolla, California, USA. mark.j.atkinson@pfizer.com
Stewart
William C
WC
Fain
Joel M
JM
Stewart
Jeanette A
JA
Dhawan
Ravinder
R
Mozaffari
Essy
E
Lohs
Jan
J
D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000009:adverse effects / Q000627:therapeutic use*; D005163:Factor Analysis, Statistical; D017144:Focus Groups; D005901:Glaucoma / Q000188:drug therapy*; D019538:Health Care Surveys; D006801:Humans; D007429:Intraocular Pressure; D008875:Middle Aged; D009798:Ocular Hypertension / Q000188:drug therapy*; D010349:Patient Compliance / Q000523:psychology / Q000706:statistics & numerical data; D017060:Patient Satisfaction / Q000706:statistics & numerical data; D011594:Psychometrics / Q000295:instrumentation*; D036301:Qualitative Research; D012646:Self Administration / Q000523:psychology*; D011795:Surveys and Questionnaires; D014481:United States
D000959:Antihypertensive Agents