Table 1

Mean score and percentage comparison of adherence, psychosocial factors and demographics between clusters (n=174)

VariablesTotalCluster 1 (Ambivalent)Cluster 2 (Sceptical)Cluster 3 (Indifferent)Cluster 4 (Accepting)
Number of subjects17430 (17.2%)53 (30.5%)51 (29.3%)40 (23.0%)
Medication adherence† ***5.87±1.874.87±1.78‡5.43 ± 1.89‡6.39 ± 1.67‡6.53±1.72‡
Necessity beliefs (Mean±SD)***18.88±4.2721.93±2.77‡18.23±1.76‡14.59±3.71‡22.93 ± 2.18‡
Concern beliefs (Mean±SD)***13.24±4.3518.83±3.66‡14.85±2.07‡11.12±2.71‡9.60±3.41‡
Illness perceptions (IP) (Mean±SD)§ ***37.13±11.0648.33±8.39‡41.72±6.23‡27.63±9.87‡34.78±8.07‡
Consequence IP§ ***4.88±2.917.30±2.55‡5.13±2.43‡2.94±2.60‡5.20±2.55‡
Timeline IP§8.20±2.448.07±2.498.51±1.857.53±2.988.73±2.18
Personal control IP§3.53±2.513.73±3.064.13±2.313.20±2403.00±2.33
Treatment control IP§ ***1.93±2.032.57 ± 2.54‡2.57 ± 1.82‡1.75±2.010.83±1.34‡
Identity IP§ ***4.51±2.917.17±2.30‡5.17±2.41‡2.35±2.50‡4.40±2.43‡
Concern IP§ ***6.85±2.828.63 ± 2.09‡7.38±2.11‡4.98±3.22‡7.20 ± 2.31‡
Coherence IP§ *2.79±2.523.53±3.563.15 ± 1.91‡2.69±2.651.88 ± 1.84‡
Emotional representation IP§ ***4.45±3.327.33±2.71‡5.68±2.56‡2.20±2.99‡3.55±2.72‡
Self–efficacy (Mean±SD)¶ **33.24±5.9631.30±6.65‡32.02 ± 6.18‡33.47±6.1136.00±3.64‡
Health literacy (Mean±SD)††3.72±2.023.13±1.943.96±1.913.80±2.113.75±2.08
Inadequate7 (23.3%)7 (13.2%)7 (17.5%)10 (19.6%)
Marginal11 (36.7%)10 (18.9%)9 (22.5%)9 (17.6%)
Adequate12 (40.0%)36 (67.9%)24 (60%)32 (62.7%)
Age58.74±12.8455.17±14.0057.85±11.4859.04±13.9262.20±11.73
White**118 (67.8%)12 (40.0%)38 (71.7%)29 (72.5%)39 (76.5%)
Female100 (57.5%)18 (60.0%)30 (56.6%)20 (50.0%)32 (62.7%)
Education higher than high school108 (62.1%)15 (50.0%)32 (60.4%)35 (68.6%)26 (65.0%)
Education
Completed 8th grade or less4 (2.3%)1 (3.3%)0 (0.0%)1 (2.0%)2 (5.0%)
Some high school15 (8.6%)5 (16.7%)3 (5.7%)5 (9.8%)2 (5.0%)
High school graduate or GED47 (27.0%)9 (30.0%)18 (34.0%)10 (19.6%)10 (25.0%)
Some college or technical school67 (38.5%)10 (33.3%)14 (26.4%)26 (51.0%)17 (42.5%)
College graduate24 (13.8%)3 (10.0%)12 (22.6%)6 (11.8%)3 (7.5%)
Graduate degree17 (9.8%)2 (6.7%)6 (11.3%)3 (5.9%)6 (15.0%)
Number of medications (Mean±SD)***7.77±3.899.07 ± 4.21‡8.19±4.03‡5.80±2.86‡8.75 ± 3.75‡
Number of illness (Mean±SD)**3.86±1.824.50 ± 2.03‡3.89±1.963.22±1.47‡4.28 ± 1.66‡
Duration of diabetes diagnosed (Mean±SD)*9.58±7.088.75±5.799.25±6.308.03 ± 7.14‡12.61 ± 8.13‡
HbA1c level*7.66±1.648.31 ± 2.14‡7.86±1.587.17 ± 1.32‡7.52±1.51
Health status‡‡ **2.64±0.802.13±0.90‡2.72 ± 0.77‡2.86 ± 0.75‡2.65±0.70
  • * p< 0.05, **p< 0.01, ***p< 0.001.

  • †Self-reported medication adherence was measured with the 8-item Morisky Medication Adherence Scale.

  • ‡Significant differences based on the post-hoc analysis.

  • §Higher scores indicate higher specific illness perceptions. Personal control, treatment control, and coherence are reverse scored.

  • ¶The score of the self-efficacy on medication use ranges from 13 to 39. 13 items on a 3 point scale. Higher scores indicate higher  levels of self-efficacy.

  • ††Heath literacy was measured with the Newest Vital Sign (NVS).

  • ‡‡One item on a 5 point scale. Higher scores indicate better self-reported health status.

  • GED, general equivalency development (or general equivalency diploma); HbA1c, haemoglobin A1c; IP, illness perception.