Smoking and Schizophrenia in Population Cohorts of Swedish Women and Men: A Prospective Co-Relative Control Study
Abstract
Objective:
Method:
Results:
Conclusions:
Method
Measures
Statistical Analysis
Results
Does Smoking Predict Subsequent Risk for Schizophrenia?
Buffer Period | Predictor Variable | Hazard Ratio | |||||
---|---|---|---|---|---|---|---|
Crude | Adjusted for Socioeconomic Statusa | Adjusted for Socioeconomic Status and Prior Drug Abusea | |||||
Estimate | 95% CI | Estimate | 95% CI | Estimate | 95% CI | ||
0 years | 1–9 cigarettes/day versus none | 2.21 | 1.90, 2.56 | 2.16 | 1.79, 2.60 | 1.92 | 1.59, 2.33 |
10 cigarettes/day versus none | 3.45 | 2.95, 4.03 | 3.35 | 2.74, 4.09 | 2.77 | 2.34, 3.43 | |
Neighborhood deprivation (mid versus low) | 1.87 | 1.43, 2.43 | 1.84 | 1.41, 2.39 | |||
Neighborhood deprivation (high versus low) | 2.00 | 2.56, 3.96 | 2.81 | 2.12, 3.73 | |||
Low parental education | 1.53 | 1.31, 1.79 | 1.56 | 1.34, 1.83 | |||
Drug abuse | 5.14 | 3.97, 6.65 | |||||
1 year | 1–9 cigarettes/day versus none | 1.89 | 1.76, 2.04 | 2.19 | 1.81, 2.65 | 1.95 | 1.61, 2.37 |
10 cigarettes/day versus none | 3.58 | 3.09, 4.15 | 3.27 | 2.75, 4.12 | 2.78 | 2.24, 3.46 | |
Neighborhood deprivation (mid versus low) | 1.82 | 1.40, 2.37 | 1.80 | 1.38, 1.34 | |||
Neighborhood deprivation (high versus low) | 2.90 | 2.19, 3.84 | 2.72 | 2.05, 3.61 | |||
Low parental education | 1.49 | 1.27, 1.74 | 1.52 | 1.30, 1.78 | |||
Drug abuse | 5.20 | 4.01, 6.75 | |||||
3 years | 1–9 cigarettes/day versus none | 2.26 | 1.93, 2.63 | 2.22 | 1.82, 2.70 | 1.95 | 1.60, 2.39 |
10 cigarettes/day versus none | 3.43 | 2.91, 4.04 | 3.39 | 2.75, 4.19 | 2.77 | 2.21, 3.47 | |
Neighborhood deprivation (mid versus low) | 1.78 | 1.35, 2.34 | 1.75 | 1.33, 2.30 | |||
Neighborhood deprivation (high versus low) | 2.83 | 2.11, 3.78 | 2.64 | 1.97, 3.55 | |||
Low parental education | 1.44 | 1.22, 1.79 | 1.47 | 1.25, 1.74 | |||
Drug abuse | 5.57 | 4.28, 7.28 | |||||
5 years | 1–9 cigarettes/day versus none | 2.14 | 1.82, 2.53 | 2.13 | 1.72, 2.64 | 1.86 | 1.50, 2.31 |
10 cigarettes/day versus none | 3.38 | 2.85, 4.01 | 3.38 | 2.70, 4.22 | 2.71 | 2.13, 3.45 | |
Neighborhood deprivation (mid versus low) | 1.88 | 1.40, 2.54 | 1.85 | 1.37, 2.49 | |||
Neighborhood deprivation (high versus low) | 2.92 | 2.13, 4.02 | 2.72 | 1.97, 3.75 | |||
Low parental education | 1.45 | 1.22, 1.73 | 1.49 | 1.25, 1.77 | |||
Drug abuse | 6.09 | 4.62, 8.05 |
![](/cms/10.1176/appi.ajp.2015.15010126/asset/images/large/appi.ajp.2015.15010126f1.jpeg)
Hazard Ratio | |||||||
---|---|---|---|---|---|---|---|
Crude | Adjusted for Socioeconomic Statusa | Adjusted for Socioeconomic Status and Prior Drug Abusea | |||||
Time Lag | Predictor Variable | Estimate | 95% CI | Estimate | 95% CI | Estimate | 95% CI |
0 years | Light smoking versus none | 2.15 | 1.25, 3.44 | 2.05 | 1.29, 3.27 | 1.62 | 1.00, 2.62 |
Heavy smoking versus none | 3.80 | 1.19, 6.60 | 3.45 | 1.97, 6.07 | 2.21 | 1.11, 4.42 | |
Neighborhood deprivation (mid versus low) | 0.86 | 0.56, 1.33 | 0.86 | 0.55, 1.33 | |||
Neighborhood deprivation (high versus low) | 1.51 | 0.89, 2.55 | 1.40 | 0.83, 2.36 | |||
Low parental education | 1.11 | 0.67, 1.85 | 1.07 | 0.65, 1.79 | |||
Drug abuse | 6.42 | 3.48, 11.85 | |||||
1 year | Light smoking versus none | 2.15 | 1.33, 3.48 | 2.04 | 1.27, 3.29 | 1.60 | 0.97, 2.63 |
Heavy smoking versus none | 3.44 | 1.91, 6.20 | 3.10 | 1.70, 5.64 | 1.96 | 0.95, 4.06 | |
Neighborhood deprivation (mid versus low) | 0.87 | 0.55, 1.37 | 0.86 | 0.55, 1.36 | |||
Neighborhood deprivation (high versus low) | 1.59 | 0.93, 2.71 | 1.47 | 0.86, 2.51 | |||
Low parental education | 1.11 | 0.66, 1.87 | 1.07 | 0.64, 1.81 | |||
Drug abuse | 6.65 | 3.55, 12.45 | |||||
3 years | Light smoking versus none | 2.16 | 1.26, 3.68 | 2.05 | 1.20, 3.49 | 1.77 | 1.02, 3.05 |
Heavy smoking versus none | 3.58 | 1.88, 6.80 | 3.21 | 1.65, 6.23 | 2.39 | 1.09, 5.24 | |
Neighborhood deprivation (mid versus low) | 0.96 | 0.57, 1.61 | 0.96 | 0.57, 1.61 | |||
Neighborhood deprivation (high versus low) | 1.89 | 1.03, 3.48 | 1.80 | 0.99, 3.29 | |||
Low parental education | 0.90 | 0.48, 1.69 | 0.89 | 0.47, 1.66 | |||
Drug abuse | 4.20 | 1.95, 9.03 |
Could This Association Arise From Smoking Onset During Illness Prodrome?
Is There a Dose-Response Relationship Between Smoking and Risk for Schizophrenia?
COPD | Schizophrenia | Nonaffective Psychosis | |||||
---|---|---|---|---|---|---|---|
Category | Reported Smoking Before Pregnancy, at Registration, and at Week 30–32a | Estimate | 95% CI | Estimate | 95% CI | Estimate | 95% CI |
Reference | (0, 0, 0) | ||||||
1 | (1–9, 0, 0) | 1.45 | 1.07, 1.97 | 1.14 | 0.46, 2.83 | 1.14 | 0.85,1.53 |
2 | (≥10, 0, 0) | 1.10 | 0.69, 1.76 | 0.86 | 0.21, 3.52 | 1.70 | 1.22, 2.36 |
3b | (+, 1–9, 0) and (+, ≥10, 0) | 2.60 | 1.80, 3.74 | 0.60 | 0.08, 4.29 | 1.70 | 1.15, 2.49 |
4 | (+, +, 1–9) | 4.70 | 2.85, 5.72 | 2.58 | 1.32, 5.05 | 2.33 | 1.86, 2.93 |
5 | (+, +, ≥10) | 10.83 | 8.70,13.47 | 3.11 | 1.13, 8.60 | 2.84 | 2.01, 4.01 |
Does the Smoking-Schizophrenia Association Arise From Key Potential Confounders?
Does the Smoking-Schizophrenia Association Arise From Shared Familial/Genetic Risk Factors?
Full Sisters | Half Sisters | Cousins | All | |||||
---|---|---|---|---|---|---|---|---|
Comparison | Estimate | 95% CI | Estimate | 95% CI | Estimate | 95% CI | Estimate | 95% CI |
1–9 cigarettes/day versus none | 1.48 | 1.37, 1.59 | 1.59 | 1.41, 1.80 | 1.65 | 1.55, 1.74 | 1.64 | 1.57, 1.71 |
≥10 cigarettes/day versus none | 2.18 | 1.88, 2.53 | 2.54 | 1.98, 3.24 | 2.71 | 2.42, 3.04 | 2.67 | 2.47, 2.92 |
Disorder and Comparison | Monozygotic Twins | Full Sisters | Half Sisters | Cousins | ||||
---|---|---|---|---|---|---|---|---|
Estimate | 95% CI | Estimate | 95% CI | Estimate | 95% CI | Estimate | 95% CI | |
Nonaffective psychosisb | (N=3,790) | (N=575,352) | (N=153,938) | (N=1,424,963) | ||||
1–9 cigarettes/day versus none | 1.30 | 1.07, 1.56 | 1.49 | 1.38, 1.60 | 1.59 | 1.52, 1.66 | 1.64 | 1.56, 1.74 |
≥10 cigarettes/day versus none | 1.69 | 1.17, 2.44 | 2.21 | 1.92, 2.55 | 2.53 | 2.32, 2.75 | 2.70 | 2.42, 3.01 |
COPDc | (N=3,802) | (N=576,878) | (N=154,442) | (N=1,427,178) | ||||
1–9 cigarettes/day versus none | 1.71 | 1.45, 2.00 | 2.06 | 1.94, 2.18 | 2.26 | 1.7, 2.36 | 2.37 | 2.25, 2.51 |
≥10 cigarettes/day versus none | 2.89 | 2.10, 3.99 | 4.23 | 3.76, 4.77 | 5.12 | 4.72, 5.55 | 5.63 | 5.05, 6.27 |
Discussion
Prospective Prediction of Risk
Dose-Response Relationship
The Role of Confounders
The Role of Common Familial/Genetic Risk Factors
Limitations
Conclusions
Supplementary Material
References
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