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Table 2 Operating Characteristics for Various Predictive Models and Definitions of Substantial Weight Gain

From: Early evaluation of patient risk for substantial weight gain during olanzapine treatment for schizophrenia, schizophreniform, or schizoaffective disorder

  

Evaluated from Study 1

Based on validation dataset (Study 2)

SWGa

Predictive Modelb

EWG cut-off

N

Sensitivity,c %

Specificity,d %

PPVe %

NPVf %

+TEST n (%)g

+SWG n (%)h

Sensitivity,i %

Specificity,j %

PPVk %

NPVl %

5 kg

WG at 1 wk

0.5 kg

669

54.0

65.5

61.6

58.1

297 (44.4)

339 (50.7)

49.1

73.9

69.2

54.8

5 kg

WG at 2 wks

1.1 kg

667

60.1

71.1

68.1

63.4

298 (44.7)

338 (50.7)

56.4

70.2

68.9

57.9

5 kg

WG at 3 wks

1.4 kg

669

65.9

70.2

69.6

66.6

322 (48.1)

340 (50.8)

63.6

70.2

71.4

62.3

5 kg

WG at 4 wks

1.9 kg

668

70.9

72.8

72.6

71.1

329 (49.3)

337 (50.4)

67.3

71.7

74.0

64.7

7 kg

WG at 1 wk

0.6 kg

669

54.7

68.3

53.1

69.7

273 (40.8)

265 (39.6)

53.7

76.7

61.1

70.8

7 kg

WG at 2 wks

1.3 kg

667

62.5

69.7

57.5

74.0

287 (43.0)

264 (39.6)

65.9

70.5

60.0

75.4

7 kg

WG at 3 wks

1.7 kg

669

68.4

71.2

61.1

77.4

298 (44.5)

266 (39.8)

73.2

73.8

65.2

80.4

7 kg

WG at 4 wks

2.2 kg

668

69.2

73.6

63.0

78.6

289 (43.3)

263 (39.4)

68.3

80.0

70.0

78.7

7 kg

BC alone

N/A

667

62.4

54.7

47.3

69.1

347 (52.0)

263 (39.4)

70.7

38.3

43.9

65.7

7 kg

WG at 1wk+BC

N/A

661

60.3

62.9

51.6

70.7

306 (46.3)

262 (39.6)

65.9

57.6

51.9

70.8

7 kg

WG at 2wks+BC

N/A

660

66.7

66.9

56.9

75.4

306 (46.4)

261 (39.5)

68.3

65.0

57.1

75.0

7 kg

WG at 3wks+BC

N/A

661

68.4

70.6

60.6

77.2

297 (44.9)

263 (39.8)

68.3

68.3

59.6

75.9

7 kg

WG at 4wks+BC

N/A

660

71.9

72.8

63.2

80.0

296 (44.8)

260 (39.4)

80.5

76.3

70.2

84.9

10 kg

WG at 1 wk

0.7 kg

669

53.0

64.1

30.1

82.4

266 (39.8)

151 (22.6)

45.8

68.8

31.4

80.3

10 kg

WG at 2 wks

1.5 kg

667

55.7

68.9

34.0

84.4

244 (36.6)

149 (22.3)

58.3

67.9

35.9

84.1

10 kg

WG at 3 wks

2.0 kg

669

68.2

68.7

38.9

88.1

265 (39.6)

151 (22.6)

66.7

67.9

39.0

86.9

10 kg

WG at 4 wks

2.6 kg

668

68.5

71.7

41.0

88.8

249 (37.3)

149 (22.3)

66.7

76.6

47.1

88.1

10 kg

BC alone

N/A

667

60.3

55.6

28.4

82.7

320 (48)

151 (22.6)

75.0

39.0

27.7

83.3

10 kg

WG at 1wk+BC

N/A

661

60.9

63.7

33.2

84.6

277 (41.9)

151 (22.8)

54.2

52.6

26.5

78.4

10 kg

WG at 2wks+BC

N/A

660

63.1

67.9

36.4

86.3

258 (39.1)

149 (22.6)

58.3

63.6

33.3

83.1

10 kg

WG at 3wks+BC

N/A

661

70.9

70.0

41.2

89.0

260 (39.3)

151 (22.8)

70.8

68.8

41.5

88.3

10 kg

WG at 4wks+BC

N/A

660

67.1

71.6

40.8

88.2

245 (37.1)

149 (22.6)

79.2

69.7

45.2

91.4

7%

WG at 1 wk

0.7%

669

53.8

66.0

59.9

60.2

292 (43.6)

325 (48.6)

50.9

75.0

69.2

58.1

7%

WG at 2 wks

1.6%

667

61.0

69.5

65.2

65.5

302 (45.3)

323 (48.4)

62.3

71.4

70.2

63.6

7%

WG at 3 wks

2.0%

669

69.2

72.1

70.1

71.3

321 (48.0)

325 (48.6)

64.2

75.5

73.9

66.1

7%

WG at 4 wks

2.7%

668

70.6

76.2

73.5

73.5

310 (46.4)

323 (48.4)

73.6

75.0

76.5

72.0

7%

BC alone

N/A

667

64.2

57.2

58.2

63.3

354 (53.1)

321 (48.1)

66.0

56.3

62.5

60.0

7%

WG at 1wk+BC

N/A

661

60.6

63.9

61.2

63.4

317 (48.0)

320 (48.4)

66.0

68.1

70.0

64.0

7%

WG at 2wks+BC

N/A

660

62.3

66.7

63.5

65.5

312 (47.3)

318 (48.2)

62.3

68.8

68.8

62.3

7%

WG at 3wks+BC

N/A

661

65.3

71.3

68.1

68.6

307 (46.4)

320 (48.4)

64.2

70.8

70.8

64.2

7%

WG at 4wks+BC

N/A

660

69.2

72.8

70.3

71.8

313 (47.4)

318 (48.2)

69.8

80.9

80.4

70.4

  1. aSWG (substantial weight gain) defined as at least 5, 7, 10 kg, and 7% increase from baseline at Week 30 (Study 1) or Week 28 (Study 2).
  2. bFor each combination of SWG definition (≥ 5, 7, 10 kg, or 7%) and set of predictors (baseline characteristics [BC] and/or weight gain [WG] at 1, 2, 3, or 4 weeks), the prediction rules (classification scores) were constructed with linear discriminant analysis models. When early weight gain is used as a single predictor, the estimated cut-off for early weight gain (in kg or % change) is shown at the time at which early weight gain was assessed. Baseline characteristics, when included in the prediction rules for substantial weight gain (alone or in combination with early weight gain) were age, sex, BMI, and Caucasian ethnicity.
  3. cSensitivity, proportion of patients with SWG that were correctly predicted (estimated using leave-one-out cross validation).
  4. dSpecificity, proportion of patients with no SWG that were correctly predicted (estimated using leave-one-out cross validation).
  5. ePositive predictive value, proportion of patients predicted to have SWG who had substantial weight gain (estimated using leave-one-out cross validation).
  6. fNegative predictive value, proportion of patients predicted not to have SWG who did not have substantial weight gain (estimated using leave-one-out cross validation).
  7. gNumber of patients (%) predicted to have substantial weight gain.
  8. hNumber of patients (%) who met the criteria for substantial weight gain as defined in the first column of this table. Number and percent of patients with SWG for a given defined SWG vary slightly because values are based on subjects included in the model who had non-missing values,
  9. iSensitivity of prediction rule derived from Study 1 data as estimated from validation data (Study2).
  10. jSpecificity of prediction rule derived from Study 1 data as estimated from validation data (Study2).
  11. kPositive predictive value of prediction rule derived from Study 1 as estimated from validation data (Study2).
  12. lNegative predictive value of prediction rule derived from Study 1 as estimated from validation data (Study2).
  13. Abbreviations: SWG, substantial weight gain; EWG, early weight gain; PPV, positive predictive value; NPV, negative predictive value; WG, weight gain; N/A, not applicable.
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BMC Psychiatry

ISSN: 1471-244X

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