Elmer Dale McDaniel seeks reversal of the decision of the Secretary of Health and Human Services denying him disability benefits. On review before the district court under § 205(g) of the Social Security Act, 42 U.S.C. § 405(g), the Secretary's decision was upheld as supported by substantial evidence. We are unable to agree with the district court's finding and therefore vacate and remand.

On February 13, 1978, McDaniel, then a twenty-four-year-old house painter, suffered a close-range gunshot wound to the abdomen which produced multiple blood vessel injury to the bowel and perforation of the stomach and small bowel. The bullet lodged in the left side of the third lumbar vertebra, causing nerve injury, especially to the left lower extremity. Corrective surgery was performed on February 13 and 14 and March 22, 1978. Upon his release from the hospital on April 4, 1978, McDaniel was experiencing bowel dysfunction, including uncontrollable diarrhea and constipation; weakness in the lower left extremity; and a total left foot drop. He was required to wear a short-leg brace and use a crutch to walk.

On March 31, 1978, McDaniel filed an application for disability benefits, alleging that he became disabled on February 13, 1978. The application was denied initially and on reconsideration by the Social Security Administration. On November 30, 1978, the Administrative Law Judge (ALJ) heard the case de novo and determined that McDaniel was not disabled because his impairments did not last the requisite twelve-month period. The Appeals Council approved the ALJ's decision on June 29, 1979, thus making it a final decision of the Secretary and reviewable under section 205(g) of the Social Security Act, 42 U.S.C. § 405(g). On appeal, the district court granted summary judgment in favor of the Secretary, finding that there was substantial evidence in support of her decision. The district court's judgment is now presented for review by this court.1

Judicial review of the Secretary's findings is limited to a determination of whether they are supported by substantial evidence. Section 205(g), 42 U.S.C. § 405(g).2 When an appeal is taken from a summary judgment granted in favor of the Secretary, the review functions of this court, while virtually the same as those performed by the district court, are nevertheless to be performed independently, carefully, and without any presumption that the decision of the district court is correct. Knox v. Finch, 427 F.2d 919, 920 (5th Cir. 1970).

Provision is made in section 223 of the Social Security Act, 42 U.S.C. § 423, for the payment of disability insurance benefits to eligible individuals who are "under a disability." Section 223(d)(1)(A), 42 U.S.C. § 423(d)(1)(A), defines disability as the

inability to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment which can be expected to result in death or which has lasted or can be expected to last for a continuous period of not less than 12 months.

Moreover, an individual shall be determined to be under a disability

only if his physical or mental impairment or impairments are of such severity that he is not only unable to do his previous work but cannot, considering his age, education, and work experience, engage in any other kind of substantial gainful work which exists in the national economy, regardless of whether such work exists in the immediate area in which he lives, or whether a specific job vacancy exists for him, or whether he would be hired if he applied for work.

Section 223(d)(2)(A), 42 U.S.C. § 423(d)(2)(A).

The burden is on the individual seeking the disability insurance benefits to prove that he is under a disability within the terms of the Act. Section 223(d)(5), 42 U.S.C. § 423(d)(5). However, once the claimant meets the burden of showing that he cannot perform his usual line of work, the burden shifts to the Secretary to show that considering his age, education, and work experience, the claimant is able to perform some other kind of substantial, gainful work available in the national economy. Western v. Harris, 633 F.2d 1204 (5th Cir. 1981).

Although our review function on appeal from the Secretary's decisions is limited and consequently the reversal of those decisions is infrequent ,3 we must nevertheless review the record in its entirety in order to fulfill our duty of ensuring the reasonableness of the decision reached. Simmons v. Harris, 602 F.2d 1233, 1236 (5th Cir. 1979). Keeping in mind our limited but essential appellate function, we nevertheless hold that such substantial evidence does not support the Secretary's finding that McDaniel was not disabled because, prior to the expiration of the twelve-month disability period,4 he had so recovered from his injury that he could engage in substantial gainful work existing in the national economy.

The Secretary found, and we agree, that McDaniel satisfied his burden of proving that his impairments preclude his return to his previous work as a house painter. However, the Secretary, relying on expert medical opinions provided by four examining physicians,5 found that McDaniel had the residual functional capacity to engage in numerous types of sedentary work.

The Secretary's reliance on these medical opinions is misplaced for several reasons. Each of the opinions was rendered within four months of the claimant's injury and, consequently, consisted of predictions that the still-disabled McDaniel's condition would improve. None of the examining physicians, however, stated that the improvements would occur within the statutory twelve-month disability period. Moreover, a medical opinion rendered by Dr. Harry Ledbetter on April 5, 1979, well over a year after the injury, and based on the most recent examination of the claimant, actually supports a finding that no improvement in McDaniel's condition occurred during the twelve months following the injury.6 Thus, the earlier, positive prognoses based on observations made less than four months following the injury were improperly relied upon by the Secretary in the face of Dr. Ledbetter's more recent opinion based on actual observation of the claimant's condition more than a year after the injury.

The Secretary also asserts, without supporting vocational evidence, that there exists in the national economy substantial gainful work of a sedentary nature available to one with McDaniel's impairments, age, and educational level.7 The Secretary's assertions were not supported by the expert medical evidence, which on the whole did not address the specific issue of McDaniel's ability to work in particular jobs.8 Nor did the Secretary rely on vocational testimony in determining what jobs would be available that McDaniel is capable of performing. This circuit has required in the past that the Secretary rely on evidence (rather than suppositions) of the existence of employment positions in the economy that the claimant could fill. See Lewis v. Weinberger, 515 F.2d at 584, 587-88 (5th Cir. 1975); Daniel v. Gardner, 390 F.2d 32 (5th Cir. 1968). In the absence of medical testimony that McDaniel is not physically disabled (or that he can do work of a sedentary nature), we cannot accept the Secretary's suppositions that the claimant might be able to perform certain available types of employment, without more, as substantial evidence in support of the finding of non-disability. See Mims v. Califano, 581 F.2d 1211, 1215-16 (5th Cir. 1978); Williams v. Finch, 440 F.2d 613, 615-16 (5th Cir. 1971).

Based on the absence of any evidence that McDaniel is not physically disabled or that there is substantial gainful work existing in the national economy which he can do , we find that the Secretary's decision is not supported by substantial evidence. We remand the case to the district court so that it may issue an appropriate order directing the Secretary to grant the appellant the disability benefits to which he is entitled in accordance with this opinion.

REVERSED AND REMANDED.