. Author manuscript; available in PMC: 2015 Nov 1.

Published in final edited form as: J Am Acad Child Adolesc Psychiatry. 2014 Sep 3;53(11):1191–1205.e4. doi: 10.1016/j.jaac.2014.08.005

Table 3.

Child, Family, and Social Environment Characteristics of Each Irritability Trajectory Class

	C1 Low, Decreasing Irritability (norm; ref)	C2 Medium, Decreasing Irritability	C3 High, Steady Irritability	C4 Initially Very High but Decreasing Irritability	C5 High, Increasing Irritability	χ²	df	p

n	2675	923	236	468	95

Race/Ethnicity						43.79	12	<.001

White/European-American (Ref)	57%	23%	13%	4.1%	3.5%

African-American	61%	21%	10%	6.3%	1.9%

Odds Ratio		.76^*	.55^*	.99	.38^*

Hispanic/Latino(a)	64%	21%	9.6%	4.5%	1.6%

Odds Ratio		.76^*	.52^*	.66	.35^*

Other	63%	18%	10%	6.3%	2.5%

Odds Ratio		.73	.70	1.38	.66

Education						30.14	12	.003

College or graduate school (Ref)	66%	20%	9.2%	1.9%	2.4%

Some college or tech school	64%	22%	8.9%	3.7%	1.8%

Odds Ratio		1.03	.81	1.79	.72

High school or equivalent	59%	22%	11%	5.9%	2.7%

Odds Ratio		1.09	.97	2.87^*	1.13

Less than high school	59%	20%	12%	7.2%	1.9%

Odds Ratio		.95	1.12	3.59^*	.84

Relationship Status						27.36	8	.001

Married (Ref)	67%	20%	7.2%	3.7%	1.8%

Cohabitating	60%	22%	11%	5.3%	2.2%

Odds Ratio		1.14^a	.1.72^b ^*	1.03^a	1.66^ab

Single	58%	21%	13%	6.5%	2.4%

Odds Ratio		1.13^a	2.22^b ^*	1.23^a	1.98^ab

Family Instability (Birth-Y3)						51.10	24	.001

Married – same partner (Ref)	66%	21%	6.8%	3.8%	1.8%

Cohabitating – same partner	61%	20%	11%	5.1%	2.0%

Odds Ratio		.96	1.92^*	.95	1.52

Married or Cohabitating

1–2 partner transitions	60%	24%	8.0%	5.2%	2.4%

Odds Ratio		1.14	1.37	.90	1.76

3+ partner transitions	62%	20%	11%	4.6%	2.1%

Odds Ratio		.93	1.87^*	.76	1.54

Single Mother

No partner transitions	60%	20%	12%	5.1%	3.0%

Odds Ratio		.95	2.07^*	.87	2.39^*

1–2 partner transitions	54%	23%	12%	8.3%	2.0%

Odds Ratio		1.23	2.42^*	1.50	1.78

3+ partner transitions	61%	17%	14%	5.0%	1.8%

Odds Ratio		.84	2.47^*	.76	1.86

Child Sex						15.01	4	.005

Female (Ref)	63%	21%	9.0%	4.8%	2.0%

Male	59%	21%	12%	5.9%	2.3%

Odds Ratio		1.02	1.42^*	1.29	1.25

Neighborhood (Y3)						F rank	df	p

Witnessed Violence (freq.)	1.55 (4.5)	1.95 (4.7)	2.56 (5.7)	3.21 (6.5)	1.70 (3.6)	40.76	4, 3295	<.001

Victim of Violence (freq.)	.20 (1.9)	.36 (2.6)	.41 (2.6)	.70 (3.3)	.12 (.45)	18.74	4, 3295	.001

						F	df	p

Loitering	.23 (.28)^a	.28 (.30)^b	.35 (.31)^c	.40 (.33)^c	.32 (.32)^bc	21.64	4, 3241	<.001

Social Support	.65 (.23)^a	.65 (.23)^a	.59 (.24)^b	.55 (.24)^b	.58 (.24)^b	9.51	4, 3273	<.001

Age at Child’s Birth	25.6 (6.0)^a	25.9 (5.8)^b	24.4 (5.5)^ab	23.8 (5.5)^ab	24.6 (6.2)^ab	3.45	4, 4368	.008

Material Hardship	1.01 (1.5)^a	1.20 (1.6)^b	1.45 (1.8)^b	1.51 (1.8)^b	1.63 (1.9)^b	10.49	4, 4035	<.001

Aggravation in Parenting	1.11 (.66)^a	1.22 (.65)^b	1.35 (.71)^bc	1.51 (.72)^c	1.26 (.67)^abc	22.24	4, 3554	<.001

Parent-Child Conflict Tactics (Y3)

Nonviolent Discipline	.51 (.28)^a	.60 (.28)^b	.62 (.29)^b	.63 (.29)^b	.63 (.23)^ab	21.08	4, 3291	<.001

Harsh Parenting	.13 (.13)^a	.18 (.15)^b	.20 (.14)^b	.23 (.17)^c	.21 (.15)^bc	40.11	4, 3291	<.001

Child Internalizing symptoms						45.14	8, 4626	<.001

Y3	.30 (.22)^a	.35 (.25)^b	.45 (.26)^c	.59 (.29)^d	.44 (.27)^ce

Y5	.17 (.16)^f	.26 (.21)^g	.36 (.29)^h	.35 (.23)^hi	.34 (.26)^hi

Y9	.11 (.12)^j	.22 (.18)^k	.34 (.23)^h	.17 (.15)^k	.61 (.48)^l

Child Externalizing symptoms						41.12	8, 4626	<.001

Y3	.49 (.29)^a	.65 (.31)^b	.85 (.35)^c	1.04 (.32)^d	.91 (.48)^cd

Y5	.38 (.31)^e	.50 (.30)^f	.67 (.36)^g	.63 (.36)^fgh	.71 (.38)^h

Y9	.08 (.09)ⁱ	.22 (.13)^j	.37 (.19)^k	.14 (.10)^l	.69 (.37)^h

Other Reports of Irritability

Father Report Y3	.37 (.43)^a	.54 (.45)^b	.63 (.48)^bc	.75 (.48)^cd	.87 (.54)^d	33.56	4, 1755	<.001

Teacher Report Y9	.23 (.41)^a	.36 (.53)^b	.50 (.59)^c	.29 (.46)^ab	.75 (.62)^d	32.75	4, 2232	<.001

Note: n refers to number of children in each irritability trajectory class. Race/ethnicity was determined by maternal self-reported race and ethnicity. Education refers to maternal educational level. Freq. = frequency, i.e., the number of times in the past year the mother reported witnessing or being a victim of violence; ref = reference for odds ratio; Y1 = child age 1, etc.

^a-l

Different superscripts indicate significant pair-wise comparisons.

Odds ratio significantly different from 0 (p < .05). Aggravation in parenting, parent-child conflict tactics, neighborhood characteristics, family instability, internalizing and externalizing, and father- and teacher-report irritability measures are detailed in Supplement 1, available online. Externalizing excludes overlapping items used in irritability scale. Measures taken at year 1 unless otherwise indicated. Significance tests and odds ratios calculated while controlling for key child/family characteristics (maternal education, age, relationship status, race/ethnicity, child gender).