8% in general population with hypertension; up to 20% in patients with resistant hypertension. Although obstructive sleep apnea is listed as a cause of secondary hypertension, RCTs on the effects of continuous positive airway pressure on lowering BP in patients with hypertension have produced mixed results (see Section 5.4.4 for details). For a list of frequently used drugs causing hypertension and accompanying evidence, see Table 14. BP indicates blood pressure; CT, computed tomography; DOC, 11-deoxycorticosterone; IGF-1, insulin-like growth factor-1; IV, intravenous; MAO, monamine oxidase; MRI, magnetic resonance imaging; MRA, magnetic resonance arteriography; NSAIDs, nonsteroidal anti-inflammatory drugs; OH, hydroxylase; and RCT, randomized clinical trial. Table 13. Continued Prevalence Clinical Indications Physical Examination Screening Tests Additional/Confirmatory Tests with somewhat larger effects in women than in men.S5.3-3 Low birth weight from other causes also contributes to higher BP in later life.S5.3-4 5.4. Secondary Forms of Hypertension Recommendations for Secondary Forms of Hypertension COR LOE Recommendations I C-EO 1. Screening for specific form(s) of secondary hypertension is recommended when the clinical indications and physical examination findings listed in Table 13 are present or in adults with resistant hypertension. IIb C-EO 2. If an adult with sustained hypertension screens positive for a form of secondary hypertension, referral to a physician with expertise in that form of hypertension may be reasonable for diagnostic confirmation and treatment. Synopsis A specific, remediable cause of hypertension can be identified in approximately 10% of adult patients with hypertension.S5.4-1 If a cause can be correctly diagnosed and treated, patients with secondary hypertension can achieve a cure or experience a marked improvement in BP control, with reduction in CVD risk. All new patients with hypertension should be screened with a history, physical examination, and laboratory inves- tigations, as recommended in Section 7, before initiation of treatment. 